Wednesday, December 29, 2010

Divine Intervention, Part II

In a previous post I talked about a new magic system for clerics. Here's the next big chunk, the face cards. In this system, Face cards always have a "cost" of 10 to play. They may be played in one of two forms.


A face card may summon a creature to aid the caster. The creature persists for one phase of combat or until it is slain, whichever comes first. Each class of card will basically have a set stat block to reference and allow a stock critter to be thrown down easily.
  • JACK: Cardinal "Striker"
  • KING: Fixed "Tank"
  • QUEEN: Mutable "Special Team"
The suit of the card is also relevant. In any event, the creature has the associated Element attached to it. For example, a Club summons some sort of Fire creature. Any other effect that plays off of fire will affect the creature accordingly. Next, there is a default creature type (although the GM/player should feel free to change this to a pantheon specific critter). Finally, when the creature is voluntarily dispelled by the caster prior to the spell's normal expiration, there is an aftereffect which occurs immediately; it is equal to an Effect 1 card of the same suit. For example, if a Fire Salamander (Club) summon is dispelled, then a Smite dealing 1 damage immediately goes off.
  • HEARTS: Water. Nymph.
  • DIAMONDS: Earth. Gnome.
  • SPADES: Air. Sylph.
  • CLUBS: Fire. Salamander.


Face cards may also be used to invoke potent aspects. These generally effect the caster themselves and have an aftereffect which lasts until the end of the phase.

  • JACKS (Version A): When played, treat the jack as a normal number card with an effect of "4." Aftereffect: The caster is considered to have an ace of the same suit in their hand until the end of the phase.
  • JACKS (Version B): Any creatures targeted by the caster within an area of effect are subjected to the magic, which is identical to a potency 1 version of the same suit (for example, the Jack of Clubs creates an AOE equal to the caster's Fire score). The area of effect is equal to the caster's relevant elemental attribute. Aftereffect: The caster is considered to have an ace of the same suit in their hand until the end of the phase.
  • KINGS: Kings generate a powerful aura surrounding the caster. The aura's size is equal in hexes to the relevant elemental attribute (for example, the King of Clubs creates an aura equal to the caster's Fire score). The caster may choose to allow the spell to effect any creatures he or she wishes within the aura.
    - Hearts (Water): +1D to all saving throws to avoid taking damage
    - Clubs (Fire): +1D to all attack rolls
    - Diamonds (Earth): +1 to Dodge Score
    - Spades (Air): Move the creature one square.
  • QUEENS: Queens unleash powerful transformative forces within the caster and represent potent self-buffs. First, the result of the "cost" roll changes the caster's relevant Elemental Attribute to the result if it is higher as well as all derived attributes. For example, casting the Queen of Diamonds might allow a caster to perform a superhuman feat of strength as their ENC load limit increases with a higher EARTH score. Next, the caster gains the following benefit:
    - Hearts (Water): Regenerate 1 wound every round
    - Clubs (Fire): +1 Damage
    - Diamonds (Earth): +1 Soak
    - Spades (Air): +1 Speed and +1 to Dodge Score vs. OAs; +1D to any evasive moves


I think we have a relatively compact system that covers all your basic combat magic. There are two broad classes of magic: Red/Defensive and Black/Offensive (named for the suits). Those subdivide down into the suits: Healing (Hearts), Warding (Diamonds), Smiting (Clubs), and Command/Movement (Spades). Within each suit, there are five types of spells: A standard, common numerical version, a summoning spell (with three variants), a self-buff, a nova/AOE, and a group buff.

The standard, common numerical version should be most common as it has the lowest cost. The other spells are potent but will likely allow the GM to retaliate later.

I think this meets the Rule of 7. The broad outlines can be remembered without reference to a table. I expect a table to be needed for face cards and summons but even those are pretty straightforward (especially the jacks). With some tweaking I may be able to make the others more standard as well.

Tuesday, December 28, 2010

Divine Intervention

I recently finished some thinking about an adaptation of a cleric type unique mechanic, just like my recent discussion of rogues.

  • Draw Seven Cards. At the start of each encounter, the cleric draws seven cards from a standard deck. The cards represent divine boons or favors which have been bestowed by their patron.
  • Invoke Boon Once Per Round Using Tactical Points. Once per round, the cleric may invoke a divine boon by expending a tactical point and playing a card. Divine boons always work (barring extraordinary circumstances) and do not require any check. If the effect is greater than one, it may be split among as many recipients as the cleric desires. For example a "Smite 3" can deal 3 points of damage to one target or 1 point of damage to three targets, or 2 to one and the third to a second.
  • Determine Effects. Apply any effects of the boon. See below.
  • Determine Cost. The TN for this check is equal to the number on the card (Ace = 1, Deuce = 2, etc). Face cards cost 10. Make a check to determine if the Invocation is free (without consequence) or if it invokes a cost. Roll Element + Ruling Planet + Archetypal Planet (See Below) using a standard dice pool against the TN. Success means the spell was free. Failure means that the DM gets to a token. Tokens may be traded in at a later time for benefits that help the opposition (more on this later).
Archetypal Correspondences: Add the following dice to a pool to determine the cost of an Invocation. Use both the Ruling Planet and the Exalted Archetype. Remember to also add a Character's primary element.
  • Saturn: Diamonds +1D, Spades +1D
  • Jupiter: Hearts +1D, Clubs +1D
  • Sun: Clubs +2D
  • Mars: Hearts +1D, Clubs +1D
  • Venus: Diamonds +1D, Spades +1D
  • Mercury: Diamonds +1D, Spades +1D
  • Moon: Hearts +2D
How to Read a Card:
  • Effect: For any number card, count the number of columns of symbols. For example, aces, deuces, and threes have the symbols arranged in one column. Fours have the symbols arranged in two columns. The only exception are fives; even though fives have three columns on the card, they are only worth "two" for effect.
  • Cost: The TN for the cost check is denoted by the actual number on the card.
  • Face Cards: Face cards are unique and special. They always have a cost of 10.
Invocations and Suits: Each suit represents a type of invocation. The red suits are generally boonful and are often best cast on allies. The black suits are often baneful and usually best to cast on enemies, although Command may be useful on allies at times.
  • Diamonds: Shield! Add Effect to Dodge for the duration of the phase.
  • Hearts: Heal! Instantly heal Effect wounds.
  • Clubs: Smite! Deal Effect wounds to targets. This blue bolt from the heavens strikes its target unerringly.
  • Spades: Command! This invocation has two variations. In the first form, slide the target(s) Effect hexes. In the second form, give effect targets a command (Fight, Freeze, or Flee). The targets must follow this command until they pass a Spirit Saving Throw (Spirit + Fixed, TN based on your relative level); they get a save at the end of each of their turns. In any event the command lapses at the end of the phase.
More on face cards next time...

Monday, December 20, 2010

Gamblin' Man

I just got back from another trip to Vegas. While sitting at the Blackjack table I had an idea about how to work this into a game a bit more elegantly than I've proposed before.

Right now, assume that every character has some sort of "tactics points." The default use of a tactics point is to get a bonus on a check. Classes may also have a specific bonus that they can get if they spend a tactics point; for example a wizard might spend a point to sling a spell or a warrior to land a crushing blow. In general, tactics points are a ticket for the player to do something at the table that takes a little extra time and puts them in the limelight. They should also use a special, unique, non-standard mechanic.

Rogues gain the use of a gambling technique.

  • Ante: The rogue immediately antes up a bid. Generally the bid is in tactics points. The rogue may also offer up Hit Points. HP may be especially likely to be anted when doubling down or splitting.
  • Pairs: The rogue may also put a bid on their first two cards being a pair.
  • Play Blackjack: Also known as 21. The rogue may double down or split as per the normal Blackjack rules. Dealer must hit soft 17s.
  • Payouts: If the rogue wins, they keep their bid it costs their foe. If they push (tie), the rogue keeps his bid and nothing happens. If the rogue gets a blackjack, then they win and it pays out 3:2. If the rogue gets a pair, his bid pays out 10:1. If it is a suited pair, it pays out 15:1.
What you can do with it:
  • Backstab. The Rogue lands a brutal blow. All payout comes from the adversary's hit points. For example, if a rogue anted up 2 tactics points to start and wins, then the rogue keeps his 2 tactics points and the enemy loses 2 HP of his own (although the rogue does not gain them). If the rogue loses then he is just out his tactics points.
  • Pick Pockets. The Rogue cleverly pilfers small items. Each point of payout is either 1/6 of a stone of ENC or one coin of an appropriate tier (copper/silver/gold). For example, if the rogue antes up 2 tactics points and wins, he either gets two coins from the victim or items up to 1/3 of a stone (usually chosen randomly).
  • Quicksilver: The Rogue seizes the initiative. All payout comes from the adversary's initiative score. The rogue's initiative score increases by the given amount. For example, say the Rogue antes up two points and wins; the foe's score drops by two and the rogue's increases by two.
Blackjack is a quick game, well suited for rapid resolution of tasks.

Odds: The house edge (DM's edge) for pairs is around 10% (using a fresh deck every time) or 35% (using one deck without shuffling). For Blackjack it is around 0.17%, making this about 50/50. This makes Blackjack a particularly attractive option against foes that are otherwise tough to affect. For example, if the Rogue normally has a 5% chance of affecting a foe, opting to play Blackjack just increased his chances significantly!


For more involved scenarios, Texas Klondike may be more appropriate.
  • ANTE: The Rogue and GM each bid 1 or 2 points (Rogue's choice) as a blind. The GM's points come from HP, gold/ENC (pick pockets), or initiative score (Rogue's choice depending on technique). The Rogue's points come from Tactics Points or HP.
  • PLAY: Each player secretly rolls two dice as their "hole" cards.
  • BID AGAIN: Conduct a round of bidding.
  • THE FLOP: Roll three dice in the center of the table as a community pool.
  • BID AGAIN: Conduct a round of bidding.
  • THE TURN: Add a fourth die to the center of the table.
  • BIG AGAIN: Conduct a round of bidding.
  • THE RIVER: Add a fifth die to the center of the table.
  • FINAL BIDS: One more round of bidding ensues.
  • DETERMINE WINNER: Whoever can assemble the best five-die "hand" wins. Use standard poker styled hierarchy of precedence: 5-of-a-kind, 4-of-a-kind, full house, 3-of-a-kind, two pairs, one pair. Winner takes the pot.
In Texas Klondike, the GM may wager other items if it is deemed acceptable. For example, if the game is being played to try and see if the Rogue can gain access to a den of thieves, each point the DM wagers up could be admission for another one of the Rogue's party members.


As above, however, there is only one round of bidding.
  • ANTE: The Rogue and GM each bid 1 point as above.
  • PLAY: Each player secretly rolls five dice as a hand.
  • BID: Conduct a round of bidding.
  • SHOW 'EW: Each player reveals their hand. Winner takes the pot.

Monday, November 22, 2010

Read on Kindle

I recently acquired a Kindle. As a side note, I love it. I'm a frequent traveler and for road warriors I think it is hard to beat. The ability to pack around a library in my hand is awesome. Moreover, the screen is actually great for reading, unlike most e-readers or computers.

Gamers might be interested to find out that the Kindle can display PDF files. I pulled S&W Core, S&W Whitebook, AD&D 1E and a few other PDFs onto the device and they displayed alright. More graphically intense files tend to have slow load times but it is tolerable. While it isn't ideal for rapidly paging through books, it is serviceable in a pinch, especially if you "tab out" the books first with bookmarks so you can quickly jump to key pages.

In any event, I am doing a lot of reading on the Kindle so I went ahead and had the Potion Shop hosted on the Kindle Store. If you have a Kindle this lets you pull down the blog in an easy to read format for a nominal fee every month. Note that I only get a small fraction, most of the subscription goes to Amazon and AT&T. I'm not doing this for the money; it is more as a convenience for any of my readers that may also appreciate being able to read blogs in Kindle format. I still do this primarily for me and as you may be used to, there may be gaps in posting. So don't be PO'd if you pay your $0.99 and I don't post every day!

Tuesday, November 16, 2010

Rethinking Ability Score Generation

After some consideration of the TROLL charts and the probabilities involved, I realized that I lost the skewed bell curve with my above and below average charts.

Here's some new rules:
  • Standard/Average: Roll 3d6. Discard the highest and lowest. Retain the remaining die.
  • Below Average: Roll 4d6. Discard the highest and lowest. Retain the lowest of the 2d6 that remain.
  • Above Average: Roll 4d6. Discard the highest and lowest. Retain the highest of the 2d6 that remain. Boxcars = 7.
  • Way Above Average: Roll 5d6. Discard the highest and lowest. Retain the highest of the 3d6 that remain. Boxcars = 7, 666 = 8.
The "discard highest & lowest" rule preserves the bell curve effect. For example, here's "below average" (invert for above average):

Value% = % ≥Probability graph
1 13.194100.000

2 27.546 86.806

3 28.009 59.259

4 20.139 31.250

5 9.491 11.111

6 1.620 1.620

Average = 2.90046296296
Spread = 1.2329578139
Mean deviation = 0.997599451303

Compare that to the modifiers created by 4d6 drop the highest:

Probability distribution:

Value% = % ≥Probability graph
1 5.787100.000

2 29.707 94.213

3 37.577 64.506

4 21.219 26.929

5 5.324 5.710

6 0.386 0.386

Average = 2.9174382716
Spread = 0.990762073825
Mean deviation = 0.767008649596

The curves aren't identical but they preserve a similar average and a similar shape, specifically, the significant decrease in a likelihood of getting a "6."

We could create a smoother curve that closer approximates the 4d6 drop the lowest curve by doing something like "roll 6d6; drop the two highest and the two lowest; take the highest of the two that remain." However, I think you start to get into diminishing returns as far as time involved and perceived complexity. It will also increase player frustration to throw away their TWO highest rolls.

Sunday, November 14, 2010

Alternate Character Statistic Generation

When I started out on Septimus I just adopted the traditional 3d6, 3-18 ability score regime we're all familiar with. However, I don't really care for it. It requires translation via a table to get ability score modifiers, it uses a totally unique dice mechanic separate from anything else in the game, and it has a lot of baggage. When someone sees that they've got a 7 for a stat they look sad. They may think they need 18s in their primary stats to succeed. While those aren't true in Septimus, it is a perception issue.

So, this is the variant system I'm toying with.

Roll 3d6. Drop the lowest and the highest. The remaining score is your ability score. Caveats:
  • If the attribute is your "prime" then roll 2d6 and pick the highest number. If you rolled boxcars, the score is 7!
    If the attribute is a double prime, then roll 3d6 and pick the highest number (i.e. drop nothing). Boxcars = 7, 666 = 8.
  • If the attribute is a "flaw" then roll 2d6 and pick the lowest remaining number. If you rolled snake eyes, the score is 0!
  • Any "4+MOD" factor in the old system (generating a range from 1 to 7) is simply "equal to your attribute."
  • Any "1+MOD" factor in the old system (generating a range from 0 to 4) is "equal to your attribute -3."
  • Improving attributes: Roll the exact same dice pool as used in character creation. If the result is greater than the current score, increase the current score by one.
The main downside of this system is that there is less granularity. Under the old system, it took three rolls before you'd go up a modifier. However, in play test, DW was actually quite unhappy about this; it felt like there was too little progress. Also, extreme results are slightly more likely. I think I'm willing to live with that however.

The upsides include:
  • No baggage.
  • Rapid stat generation; no need to cross reference a table to convert a 3-18 score to a modifier.
  • More noticeable effects at level-up/stat improvement time.
  • Commonality of mechanic.


What do these distributions look like (courtesy of troll)?


Old School, 3d6 convert to Modifier (1 = -3, 6 = +2):
Average = 3.5
Spread = 1.02288625775
Mean deviation = 0.861111111111

1 1.852100.000

2 14.352 98.148

3 33.796 83.796

4 33.796 50.000

5 14.352 16.204

6 1.852 1.852

New -- "Normal" (3d6 take the middle)
Average = 3.5
Spread = 1.37099585325
Mean deviation = 1.16666666667

Value% = % ≥Probability graph
1 7.407100.000

2 18.519 92.593

3 24.074 74.074

4 24.074 50.000

5 18.519 25.926

6 7.407 7.407

Distribution roughly appears like a bell curve, although it is really parabolic, without the aracteristic tapering at the ends. It is roughly equivalent, though; the odds of getting a 16-18 on 3d6 (the same as my "6" above) are about 5%. We're in the same ballpark above.


Old School: 4d6 drop the lowest (then convert to modifiers)
Value% = % ≥Probability graph
1 0.386100.000

2 5.324 99.614

3 21.219 94.290

4 37.577 73.071

5 29.707 35.494

6 5.787 5.787

Average = 4.0825617284
Spread = 0.990762073825
Mean deviation = 0.767008649596

The odds for a Prime are the same as my core mechanic, although obviously inverted for Flawed scores. That is, the mean increases by one (3.5 --> 4.5) and lower numbers become very unlikely.

Average = 4.47222222222
Spread = 1.40408355068
Mean deviation = 1.1975308642

Value% = % ≥Probability graph
1 2.778100.000

2 8.333 97.222

3 13.889 88.889

4 19.444 75.000

5 25.000 55.556

6 30.556 30.556

The chart doesn't reflect my "Boxcars = 7" rule, but Boxcars should occur 1/36 of the time (2.7%), and it would reduce the percentage of the time that you get a "6" as one six is a prereq for boxcars.


Old School: 5d6 drop the lowest two yields...

Probability distribution:

Value% = % ≥Probability graph
1 0.077100.000

2 1.878 99.923

3 12.037 98.045

4 33.449 86.008

5 41.165 52.559

6 11.394 11.394

Average = 4.47929526749
Spread = 0.916573125002
Mean deviation = 0.775236687698

And finally, for a so-called "Double Prime," you get this.

Average = 4.95833333333
Spread = 1.14387458844
Mean deviation = 0.901234567901

Value% = % ≥Probability graph
1 0.463100.000

2 3.241 99.537

3 8.796 96.296

4 17.130 87.500

5 28.241 70.370

6 42.130 42.130

Saturday, November 13, 2010

Septimus Test Drive

A few weeks ago before I left on the current business trip I actually ran a quick dry-run of Septimus, the code name for my homebrew system. It is nowhere near even a true "Alpha" run; it is definitely pre-Alpha. However, for me it was a major milestone to put many of these abstract thoughts on paper and roll dice with them.

Here's a quick run down on the key themes and core terminology that is emerging:

What is it: Septimus is a role playing game that focuses on exploration of archetypal themes in the context of a "generic fantasy" milleu. If using the "what if" terminology, you could say, "What if D&D was heavily influenced by gnostic thought?"

How are characters defined: Characters are defined by a series of archetypal roles and symbols. There are 10 attributes in three categories. Here is a brief overview of the character creation process.
  1. Select prime Element (Air/Water/Earth/Fire): Put one point into one of these four elements. The elements are stand-ins for player psychology and each element should appeal to a different type of player. It is very viable for one player to always pick the same element, and there is no need to "balance" a party by including all of the elements.
  2. Select prime Quality (Cardinal/Fixed/Mutable): Put one point into one of these four elements. DW suggests that I need to change the names of these, and I likely will, but for now I'm keeping the classic astrological names to keep them easy to remember. I am thinking of renaming them to figures from playing cards (Knight/King/Queen) but am leery of introducing gender-specific terms. These are the classic "roles" of an RPG party. You could relate them to offense, defense, and special teams. A balanced party should have one of each role. Luckily there are only three of them!
  3. Derive Astrological Sign. In astrology, element + quality = sign. For example, Leo is the sign of high-summer, a Fixed Fire sign. Signs are old and potent archetypes. If players want to select a sign first and then go back to derive the element/quality pairs, they can certainly do that.
  4. Derive Ruling and Detrimental Planets. Each sign is ruled by a planet, which exerts unusually strong influence. There is also a planet which is uncomfortable within each sign. Planets govern things such as skills (the arts) and other certain actions. They also govern Matter, Mind, and Spirit and the relations between them, which are important attributes.
  5. Select your Guide. All of the previous steps could be described as "nature." Your character may have been born under a certain set of stars, raised in a certain type of home, or otherwise shaped by powerful influences largely beyond their control. The Guide is the "nurture" part, often actively selected by the character. It may be a specialty, an object of worship, or an ideal.

    The Guide is another planet from the list of seven in a default setting. The planets are each associated with Classical deities so it may also be linked to those gods. For example, a player may select either Jupiter or Zeus as their Guide; either way they are equivalent, mechanically. In the future I may break this out more closely, and say that the particular aspect you identify with has additional mechanical effects (for example, "clerics" may focus on Zeus, "mages" on the planet Jupiter, and so on). You could easily have players start without a Guide and discover one through the course of play, for example, a spirit quest, meeting a hermit, or any other similar adventure.

    It is not necessary for a party to cover all of the planets although it would probably be helpful to cover a wide variety of them just to get access to a wider variety of skills and other perks. Most teams of three will tend to cover a majority of the planets without trying too hard even without coordinating their selections.
  6. Fill in Derived Matter/Mind/Spirit information: Each planet governs one of these elements. For example, Saturn is the dominance of Matter over Mind, thus you'd put a point into Matter if Saturn is either your Guide or Ruling planet. Thus you'll put two points on these attributes.
  7. Roll Dice to Generate Attribute Scores: You will now generate Attribute scores for Matter, Mind, and Spirit; Cardinal, Fixed, and Mutable; and Earth, Water, Air, and Fire. Roll 3d6 and total them to generate a score for each. For each point you've put into a category, add an extra die but total only the highest three. For example, if Earth is your Prime element, you'd roll 4d6 and take the highest three when generating your Earth score. Convert all ability scores to a modifier from -3 to +3 using the standard table. Optional: After rolling, reduce any score by -3 to add +2 to a "prime" score in the same category.
  8. Make all derived picks: Most of the Attributes have things associated with them that you can select in order to customize your character. Usually they are things like "pick 1+/-MOD" or "pick 4+/-MOD." Usually 1+/-MOD are more consequential and involved choices, so if you don't want to deal with them simply trade that attribute score down using the rules above. Some derived picks will be made for you; for example, each planet has skills associated with it, so your Ruling Planet and Guide will select two skills in each category for you.
  9. Finishing Touches: Select equipment, round out details, and tie up any odds and ends.
  • Difficulty: There are three packages for difficulty, Basic, Advanced, and Expert. Each generally is equivalent in power. Expert will give more choices and be more difficult to play effectively than Basic. This is a choice based on player skill level. New players should start with Basic and move up later if desired.
  • Primes & Flaws: You may designate any ability within a category as "Flawed." If you do so, you get one more point to spend in that category. For example, you could designate Water as "Flawed" and get two points to spend in Elements rather than one. Both could go into one element (for example, you could double tap Fire) or you can spread them out (Fire & Earth). Instead of rolling 3d6 to generate the Flawed score, roll 4d6 and total the three lowest dice. If an attribute is double tapped, then roll 5d6 and total the three highest. When trading down scores, you may subtract 3 from the Flaw and add +1 to each Prime if preferred.
It sounds complicated but really goes quite rapidly. There are relatively few choices that neatly funnel you into the next choice. You never have to choose from a list longer than around seven options and the derived attributes flow rapidly from a few initial choices.


In test I was pleased how archetypes flowed from initial choices. DW selected "water" as the element most aligned with her personality and play style, and then selected "cardinal" as she wanted an aggressive character that started things. We referenced a quick table and determined that the Cardinal Water sign is Cancer which is ruled by the Moon with Saturn in detriment. She then selected Mars as her Guide as she likes to smack stuff around.

This led to some derived skill specializations which we rapidly filled in on the character sheet (all the arts are arranged in rows by their ruling planet, so you just check off an entire row at a time). Her character was good at music, armament, and fighting due to Mars and Grammar, Hunting, and Shooting due to the Moon. She was deficient at Astronomy, Agriculture, and Riding which are the provenance of Saturn which as we recall is in Detriment in Cancer. She got +1 Matter and +1 Mind from her planets, making her a character well grounded in the physical and mental realms but perhaps less cognizant of spiritual or divine concerns.

So what did we have? Before making any fiddling choices, just focusing on the emergent core archetypes from the first few key selections, we had an introverted, energetic militant huntress. Reading articles on Cancer, Diana (of the Moon), and Mars would give lots of role playing ideas. These archetypes were supported by the mechanics of the game rather than just being a roleplaying label on paper only.

I think this also has a ton of potential for generating NPCs. You can either rapidly step through the process to rapidly generate archetypes, or if you have an archetype in mind already, start with the sign then work backwards. There is a rich tapestry of material associated with all of these elements so it is easy to find archetypal associations to explore.

What is the core mechanic: The core mechanic is a simple dice pool system based on D6s. Some sub systems utilize other mechanics but in general everything uses D6s.

  • Building Dice Pools: A general dice pool is constructed by adding +1 die for each relevant "prime" or specialty. For example, if our character above had to roll Earth + Cardinal, she'd get +1 die because Cardinal is prime but she does not have Earth prime. If an attribute is Flawed or a skill is a Detriment then subtract one from the Dice Pool. Dice Pools for core adventuring abilities like melee attacks are carefully controlled to keep them from getting out of control. The mechanic has diminishing returns built in to reduce the impact of "stacking" too many dice.
  • Reading Dice Pools: The highest die showing is normally the result of the dice pool. Each additional six adds one to the result (so boxcars = 7). Sometimes, the number of dice showing the number is relevant; for example, getting a pair of 5s would = 2.

They're called "Reserve Feats"

An interesting post over at Grognardia. James takes a brief segue into mechanics-land (something he doesn't do too often). I hadn't thought about 3.5 lately, but one of the later innovations that I actually really liked was Reserve Feats. If I played an AD&D or OD&D game with Vancian casting this is one thing I definitely think I would keep in.

A few ways you could handle it:
  • Each and every spell has a rider effect that kicks in if still memorized, either baneful or boonful. The downside to this is that you must individually balance each spell. It also gets to be a lot to keep track of at higher levels.
  • As above, but cap the number of active effects. This has fewer but still significant issues.
  • Introduce "reserve feats" a la 3.5. Basically, in 3.5, you could take feats that said things like, "Throw a mini-fireball, affects one creature, deals 1d6 damage per spell level of the highest Fire spell you have memorized." You could come up with a list of 7+/-2 Reserve Feats then let players select them. I would either allow a number of feats equal to MU Weapon Profs (so 1 at level 1, then another at level 7), or perhaps a number based on INT score + extra ones with weapon profs (to create growth with level). I'd also consider allowing players to "retrain" their Reserve feat every level up.
The advantage to this system is that it beefs up low level casters without unduly affecting higher level ones, is easy to run, and creates great "specialty" caster flavor. For example, you could actually make the schools of magic significant; someone with the Divination reserve feat would sure want to have a Divination spell memorized every day!

Saturday, November 6, 2010

Key Assumptions for a Spacefaring Game

I've been doing more brainstorming about a spacefaring game. These are some key assumptions I'd make about the setting in order to facilitate play.


ION DRIVES. The characters have access to highly efficient Ion Drive (or similar) technology allowing constant acceleration of typical spaceships from 0.1 to 1 G (or so). This makes interplanetary travel fairly rapid. For example, with constant acceleration at 1G, you can travel from Earth to Mars in a matter of days. This allows you to basically assume that players enter any tactical encounter with any reasonable relative velocity vector that they want. It could also be used in tactical encounters to generate very small thrust (say, 0.5 to 1 or even 1.5 Gs).

Reaction mass expended in an enhanced ion drive for interplanetary travel purposes is essentially negligible because we are assuming an incredibly efficient thruster (many orders of magnitude more powerful than exists today). The downside is that these drives require a lot of energy to function, from, say, a fusion reactor. Less powerful variants might be powered with fission or solar sources.

Here's a useful rule of thumb to calculate travel time: If you accelerate at A gravities to midpoint, then turnover and then decelerate at A gravities to your destination, elapsed time is approximately 4 SQRT (D/A) days, with D in astronomical units.

So to travel from Earth (1 AU) to Mars (1.5 AU) at constant acceleration of 1g, it would take: 4 * SqRt (0.5 / 1) = 2.8 days.

SOLAR SAIL. A less expensive (and lower energy) variant of the ion drive is mature solar sail technology. The advantage to this is that it is theoretically fast. It also requires very little energy and thus is probably less expensive. The downside is that it is not very maneuverable. This could be an option for players on a budget but it would prevent them from entering encounters with whatever velocity they want.

HOHMANN TRANSFERS: Interplanetary Travel without constant acceleration is done on Hohmann Transfers. Generally, for game play purposes, it is not necessary to understand how these work: it is a long time, and you can do it with limited thrust (generally two burns suffice; an initial and a final burn). Hohmann transfers are used for a few gameplay purposes:
  • Bulk cargo shipments from one orbit to another often use Hohmann transfers. For example, maybe the PCs get involved in an asteroid mining operation and need to get their bulk wares to somewhere else in the system inexpensively.
  • Sometimes a system might have a space station or other useful object on a Hohmann transfer orbit.
  • The PCs might be absurdly poor or limited on funds/local tech to old-school solid or chemical rocket technology.
  • Escape capsules might use Hohmann Transfer Orbits. This is a nice penalty for "death:" if you have to eject from your crippled spaceship, the escape pod has just enough thrust to put you into a transfer orbit. It basically means that the penalty for "death" is weeks or months of inactivity while you sit in your life raft and think about failure (or pay for a lift from an ion-drive equipped salvage ship).
You can estimate the time required for one relatively easily, however:

P^2 = A^3 (where P = time in years and A = distance in AUs)
Steps to solve (example is Earth to Mars):
  1. Add the distance of the first planet from the sun to the distance of the second planet from the sun (1 AU + ~1.5 AU)
  2. Find the semi-major axis of the transfer orbit by dividing this number in half. (2.5 AU / 2 = 1.25 AU)
  3. Solve the above equation. Use a calculator... (P = ~1.4 years)
  4. The equation gives you the time for a full orbit (i.e., Earth to Mars and back). Divide this by two to get the one way travel time. (0.7 years or around 8 months)

CHEMICAL DRIVES: Liquid and solid fuel rockets are still useful. They provide very high impulse. They are also cheap. This makes them great for tactical maneuvering on a "fighter" type spacecraft; generating 1G on an Ion Drive is not going to stack up favorably against a fighter maneuvering at 9Gs. Additionally, they are cheap and simple to operate.

The downside is that they require a lot of mass for fuel.


ION DRIVES. The Ion Drive can also be used for interstellar travel. In general, the amount of time it takes to get from one system to another with constant acceleration at >0.5G is the distance in light years plus one. So, to travel two parcsecs (about 6 LY) takes about 7 years with an ion drive. Mass consumption is significant at these distances and should probably be checked for each parsec of travel.

Over long journeys, relativistic effects can occur; for example, it traveling 3 LY (1 parsec), people on the planets age 5 years but those on the ship age only 4. if traveling 6 LY (2 parsecs), planet dwellers age 13 years and those on the ship experience only 13. The bottom line is that I don't expect PCs to travel this way most of the time, so it isn't a factor other than to understand abstractly; there may be "gypsies" that travel from system to system with ion drives at velocities which are high percentages of C that essentially accept that everything they once knew on a planet will be left behind.

SLEEPER SHIPS. Cryogenic technology allows passengers to be put into suspended animation. This allows a ship to burn up to a significant fraction of C (say, 0.05 to 0.1) but only twice (to accelerate then decelerate). Travel in this method takes decades or centuries to go even a few parsecs. The PCs might occasionally come across an old sleeper ship. Under very rare circumstances they might be forced to travel this way due to limited technology or funds. Travel in this manner might be a good way to basically start a new campaign.


There are three FTL technologies available for interstellar travel. Any or all of these may be unavailable in any given campaign. In particular, jump drives and warp drives work in a very similar manner and could easily be combined, i.e., there could be man-made wormholes. These technologies are useful within a globular cluster of systems or a spiral arm, about 20-30 parsecs in diameter.

JUMP DRIVES. Special jump drives allow travel between systems by exploiting "temporary" wormholes. The wormholes link nearby systems forming "space lanes." While temporary in astronomical terms, they generally remain stable for long durations in human terms. This allows the GM to add or remove space lanes occasionally. The wormhole is great because it allows travel that might normally be measured in parsecs to be completed in days. The downside is that both ends must be charted in order to safely jump. Additionally, these routes are predictable, which means that pirates and others often prey on them. Finally, the jump points are not always conveniently located.

More powerful jump drives allow longer jumps to occur, on the order of 1-9 parsecs. Regardless of the length of the jump, travel time is always the same (around a week). Ships in the wormhole cannot generally interact with anything outside the wormhole, and interactions within wormholes are very rare and unpredictable.

WARP DRIVE. This is based on the Alcubierre Drive. It works just like a wormhole except that the infrastructure to travel is man-made, not reliant on natural phenomena. Ships in warp drive cannot interact with the outside universe outside their warp bubbles.

HYPER DRIVES. Hyper drives allow a ship to "sidestep" into an alternative dimension (hyperspace) where travel at FTL speeds is possible. The advantage of hyperdrives is that unlike Jump or Warp drives, one can travel anywhere independently of Wormhole entrances or Warp Drive infrastructure. With a hyperdrive, it takes a number of days to travel somewhere equal to the number of lightyears + 1 (thus to go two parsecs takes a week). Hyper drive is popular with scouts and explorers (as well as pirates, recluses, or others who want to travel to obscure backwaters or avoid chokepoints and checkpoints). There are several downsides to hyperdrives:
  • Expense.
  • Fuel consumption; the vessel is constantly accelerating within the hyperspace bubble, requiring fuel expenditure.
  • Limited mass. There should be a non-linear energy cost to bring objects into hyperspace, preventing it from being useful for mass commerce.
  • Need for precise calculations. There is a significant chance, especially over longer jumps, that the ship will not end up exactly where intended. This effectively caps safe travel ranges at 1-9 parsecs per jump. The ship will likely need to drop out of hyperspace for navigational fixes on a regular basis.
  • Gravity Well sensitivity: Hyper Drives cannot be safely used close to stars or other major gravity wells. While some systems have Warp infrastructure or Wormholes at more convenient locations, a hyper-drive equipped vessel always needs to navigate to the outer edges of a system in order to safely jump. Of course, under extreme circumstances, a hyper jump can occur (for example, to escape), with unpredictable results...
  • Time. Hyperdrives can be faster for short trips of 1-2 parsecs, but anything longer is faster to do with a Jump or Warp drive.

The three technologies above are ideal for travelling distances of 1-9 parsecs at a go. They are good for traveling within one spiral arm or globular cluster of a galaxy. Travel across a galaxy requires movement rates in Kiloparsecs. Some obscure, rare, and expensive technology might allow such travel. As an example, the milky way is 30 kpc in diameter.

This technology should be rare and expensive with perhaps limited usage or requiring highly specialized ships. Alternatively, very rare natural phenomena such as the Deep Space Nine wormhole might allow such travel.


Travel between galaxies is exceedingly rare. Intergalactic travel should be a one-time event leading to dramatic changes in the campaign. Intergalactic travel is measured in megaparsecs. For example, the nearest other galaxy to the Milky Way, the Andromeda Galaxy, is 0.77 mega parsecs (770 kpc).


There are not many sentient alien life forms. The explored systems are decidedly humanocentric. As humanity has spread out, some humans have adapted to different local conditions, such as high or low gravity, but they are still decidedly homo sapiens. The exact reason for this is unknown.


The game occurs in a different "neighborhood" of the galaxy than Earth. Maybe it is a different spiral arm or globular cluster. In any event, due to the travel limitations described above, each globular cluster is fairly isolated with limited travel between them.

Alternatively, Earth has been destroyed by some cataclysmic disaster.

In any event, the theme should either be one of a fallen empire or of an isolated backwater sector.


Moore's Law states that computing power doubles every 18 months. Starting in the early 21st century, computing technology rapidly leveled off as in an S-curve. While it has advanced since that time, computing power is not exceedingly greater.

Additionally, there are strong taboos against various forms of artificial intelligence, especially AI for controlling weapons or other potentially lethal systems as well as any sort of interstellar FTL travel. Perhaps there is a history of Earth being destroyed by rogue Unmanned Systems. There is a chance that AI used for FTL travel pilotage will for some reason malfunction with potentially disastrous consequences.


There are a few ways to get stuff from the surface of a planet into orbit. They are limited. Generally, player spacecraft are not great at operating freely in an atmosphere or strong gravity well. The purpose of this is to keep the focus of action in space, not on planets. Travel to planetary surfaces should be the exception, not the rule.
  • Space Elevators: Very developed planets that regularly move large masses to orbit may have a space elevator established. This allows the PCs to pick up and drop off cargos from orbit.
  • Mass Drivers: Lower gravity planets may have large mass drivers to launch objects violently into orbit. While not good for fragile cargos, this method is highly efficient for bulk materials. A mass driver might even be able to place cargo into a Hohmann Transfer orbit.
  • Space Stations: Many planets may establish space stations as way points. For example, if traveling from a planet to its moon, it would make sense to have a station in Earth Orbit and another in Lunar orbit. Shuttles to and from the earth are designed to operate in atmosphere; those between the stations can be designed for pure vacuum operations; the final link to the lunar surface can be designed for lunar landing. If regular commerce occurs it is more viable to have a station, even a small one, and specialized rockets than to try and build a multipurpose space vehicle. Heck, even Earth today has a small manned station in low orbit.
  • Occasional orbital shuttles: The least populous and most backwards planets may just run an occasional shuttle to orbit. Cargoes might be launched with single-use rockets as needed.

In general, there are no faster than light communications. Interstellar FTL comms are limited to mail runs on FTL-drive equipped ships. Due to the prohibition on AI FTL drive operation, generally mail runs are carried on manned ships. This means that systems are relatively isolated from one another, making decisive local action important, and gives the PCs something important to do (carry mail and act as couriers). It also limits the scope/size of any sort of interstellar authority and forces decentralization.

Wednesday, November 3, 2010


I just had a lecture on human G-limits and some training. I'm not an aviator but I have flown in some high performance aircraft and pulled significant Gs. It isn't easy, and equipment/training helps.

Here's some rules of thumb for sustained Gs:

1-3 Gs: Generally no problem for people in average health
4-6 Gs: Gray out occurs. Untrained personnel or unprepared people can black out or suffer G-LOC.
7-9 Gs: Without G-training and equipment, blackout or G-LOC is likely. Even trained people will find this challenging.
10+ Gs: Generally leads to G-LOC

Partial G Suit: +1.5G
Full G Suit: Add +2.5G
Anti-G Straining: Add +3G
Adjusting seat tilt from 30 degrees to 65 degrees: +2G

Negative G is much harder to deal with; humans can handle about 1/2 that G-Load.

What this means for a Game?

As previously discussed, acceleration is the key thing for a space game that should determine scales, not velocity. Let's assume a system where 3 Gs = 1 square of movement, 6 is 2 squares, and so on. If you are accelerating at less than 3 Gs (say, a gentle 1G push) then you have a 2/6 chance of accelerating one square. A super-gentle 1/2 G push would be but a 1/6 chance.

If you assume a one minute turn, then 3G acceleration gets your velocity increased by about 1800 meters. Round it off to two clicks to make the math easy, or down to 1 click and use ~30 second turns instead of one minute turns.

With this sort of system, you'd be able to make a light burn to add 1 hex to your velocity, a moderate burn to add 2 hexes, and a strong burn to add 3. We could postulate some sort of enhancements to human physiology/g-suit technology that might make burns of10-12 G's possible that would allow adding 4 hexes to your velocity.

Alternatively, you can use an alternate G-scale (perhaps going in units of four or six instead of three). This would allow much higher velocities to be rapidly attained, and basically assume that a combination of properly reclined seats, improved G-suits, and perhaps sci-fi tech is in play to allow those greater accelerations. This would basically require hexes of 3 or 4 KM in size rather than 2 KM.

Modeling G-LOC

You could say that 1-3 Gs is no problem. Once you hit 4Gs, then you need to start making some sort of check or take damage. Bonuses to the check could be obtained from a hardy constitution/good health and high-G training (G-straining maneuvers). Moreover, appropriate equipment could give bonuses to the G's you can handle without trouble. For example, maybe having a G-Suit gives you another +3Gs of tolerance and having an acceleration couch designed for high G gives you another +3G. That would let a pilot of an optimized high-G spacecraft to pull up to 9Gs (3 hexes) without making a single check.

The G-LOC "damage" track might have three hits, or combined with some sort of "stunning" damage:
  • First Strike: Greyout. Minor impairment.
  • Second Strike: Blackout. Vision severely impaired. Other functions severely impaired.
  • Third Strike: G-LOC. You're out.
You could require folks to make one save for each category of acceleration they're exceeding their safe threshold by. So, say you are just an average Joe in a Space Civic. You have no G-protection devices. Your safe max G is 3. You initiate a maneuver that pumps you up to 9 Gs. You're going to go from just fine to "blackout" if you fail your tolerance checks. So, an experienced high-G pilot who knows how to G-strain and is in good shape might be able to take it, but the average Joe is going to be mighty close to passing out. Heck, even that simulation is pretty generous I think because most folks would actually pass out if rapidly accelerated to 9G with no protection.

Character Builder is Dead... Long live Character Builder!

I've got a DDI subscription which I got for a web based campaign that is stuttering off the runway. One of the tools I appreciated most is the Character Builder application. For those who are unfamiliar, it is a standalone little program WOTC put together which lets you easily and quickly build PCs. It actually works pretty well and is basically the only way short of reviewing the 4E Char Op boards to build a character in 4E. It honestly makes buying splat books irrelevant, which is nice.

Of course, I'm sure I'm not the only one that realized that you could get a short subscription, download Char Builder, and then cancel your DDI subscription. Every few months you could get a new subscription to download new updates. WOTC tried to crush this by limiting updates to a handful per month (so you can't spam it to a bunch of computers) and by scaling their pricing scheme to reward you for longer quarterly or annual subscriptions.

However, WOTC has announced an "upgrade," in that the old standalone character builder will now be dead. Instead, you get an internet based application. There are some actual improvements. However, I have mixed feelings about getting rid of the standalone application. I liked the utility of being able to build a character anywhere: on an airplane, while deployed, or just generally away from the internet. Now, you can only use DDI when there is internet handy. I suppose as wifi becomes more and more prevalent this is less of an issue but still, I don't love it.

From the business side, they now lock you into a continious subscription as you have no standalone option anymore. You can't pay for a one-month subscription to get the jewel in DDI's crown. You need to pay for an annual subscription to keep access to your character sheet.

I'm also concerned that they will freak out on me for sharing an account with Mrs. Nittany. If I'm traveling for work and log on from some random place and she logs on at home, will WOTC get upset at us? Who knows!

Anyways, we'll see. I'm not sure I love this new release. I think that WOTC should consider two tier pricing: a DM price that gives access to all content and a player price that just gives you the Compendium and Character Builder. I don't know if I'm willing to pay $60/year to play 4E D&D.

Tuesday, November 2, 2010

Space RPGS: Flight Models II

In my previous post I wrote about some considerations for spaceflight models, and identified the key variable as acceleration rather than velocity. I did some more thinking and research and came up with a few implementable options. Adding vectors is fun!

  • Ignore Momentum. I don't like this as it is totally unrealistic and makes a space RPG feel like any other wargame or token-based RPG.
  • Abstract Movement. You could go with a early CRPG style representation: one side lines up on the left side of the board, the other on the right, and they fight in a very abstract manner. You could have rules for maneuvering which could help for dodging attacks, or maybe range categories ("Close, Far, Disengaged...").
  • Track Each Vector's Values: You can track the speed associated with each vector for each token. For example, you could represent something's velocity as follows: "North 2, East 1, West 0, South 0." If the vehicle accelerated to the North 2 and West 1, then you'd modify the numbers to 3/0/0/0. Each turn the vessel moves in the appropriate number of squares. This works great for a small number of tokens. However, if you have multiple tokens it gets troublesome to keep track of as you basically need a separate worksheet for each vessel. Additionally, I think it is necessary to go for at least a hex based system to smooth things out. However, it is probably the easiest way to deal with 3-D movement. It is also easier to deal with higher speeds as you can just subtract X from everyone's speed in a certain direction without changing any of the relative velocities.
  • Use Two Tokens for Each Vessel: You can also use two tokens to represent velocity. In my previous example, you'd have one token representing where the ship is and a second representing where it is going, two squares to the North and one to the West. After acceleration, you'd move the second token one space to the East and one space to the North. Before moving the ship, drop a third token 3 squares to the north of the second one. The advantage of this system is that you can keep track of larger numbers of vessels with relatively little difficulty. The trouble is that you need multiple tokens/minis to run it all and as velocities get larger there is a greater chance for error to occur.
  • Trigonometry: You could use trigonometric functions to add vectors. I think this would likely require a table of look up values. It would allow you to play without minis, however.

Wednesday, October 27, 2010

Space RPGs: Flight Models

I've been thinking a lot about a space RPG lately. I never played Traveller, but I've reviewed it, and it is far too complicated. I know that Traveller spawned Elite, which in turn spawned Privateer (which was a childhood favorite game of mine), but it is just too much for me to want to run as far as rules go these days.

One problem that I've been putting some brain bytes towards is how to handle space combat. There are two approaches: realistic physics or arcade style. Video games had to deal with this too. Arcade style is popular because it is easier to grok, even if it is unrealistic. An example would be violating the law of conservation of momentum, capping maximum speeds in a vacuum at something significantly less than C (speed of light), and so on.

An RPG could go with the same sort of idea: each turn, a sub-light ship moves X squares and can make Y changes in direction. This effectively taps maximum speed at X squares. You could even justify it by saying that the sub-light technology has some sort of special property that perhaps cancels out inertia or momentum (converting velocity to heat or something).

However, this totally disregards some unique aspects of spaceflight. For example, if a ship continually accelerates at 1 MPH, its velocity will eventually get to be significantly greater than 1 MPH! One of the advantages of traveling in a vacuum is that you can get up to a great speed, especially if you have enough fuel/energy to generate thrust for 1/2 your trip. I think the solution is somewhere in between: use pseudo-newtonian rules that feel unique and space-shipish but are easy to implement.

I think the key is to focus on acceleration, not velocity. After all, if the relative velocity of the combatants is zero, you might as well be stationary.

The two things that help a lot as far as limiting factors go are:
  • Limited Acceleration due to Gs: The human body can take about 9 Gs before G-LOC occurs. Much equipment may not be able to handle that much. For example, a spindly vacuum-only ship may only be able to take 1/2 to 1 G. While that is not a limit on velocity, it does significantly limit acceleration. 1 G is about 10 m/s^2, or approx 22 MPH (so if you could accelerate from 0 to 65 MPH in one second you'd feel three gees). In another example, the Apollo trans-lunar velocity was something like 25K MPH, which is about 11,000 M/S. A 3G (30 m/s^2) burn would have to burn for something like 6 minutes to get you up to that speed.

    Note that a human body can take something like 45Gs without breaking under certain conditions. However, if you're talking about sustained, fighting capability -- 9 Gs is a good rule of thumb.
  • Limited Fuel: Unless you posit a never-ending energy source for your sci-fi world, then fuel will not be unlimited. Say your spaceship is 2000 tons, about the size of the space shuttle. Kinetic Energy = (1/2) mass * velocity ^2. A mass of 2000 tons is close to 2,000,000 kg, and the desired velocity for a 3-day moon shot is 11,000 m/s, so the energy wrapped up in that enterprise is 121,000,000,000,000 joules. By my rough reckoning that's about the amount of energy in a million gallons of gasoline, 7.5 million lbs of coal, -- assuming 100% perfect efficiency in the engine! If you could assume that you can crack uranium-235, it'd be much less (about 7.5 lbs), but the mass of the reactor would have to get added to your 2000 ton spaceship! With the exception of drives like Ion Drives or Solar Rocket Engines which are highly efficient as far as propellent usage goes (but provide very low thrust -- and thus are not tactically interesting for most PCs...), most of the other options use a ton of fuel and are propellant inefficient (TANSTAAFL). So, the bottom line is that if you limit fuel, then it will limit the "burns" that a ship can do, which limits maneuvering and acceleration.
Here's my rough estimate of how to figure out "useful" scales for tactical ship-to-ship combat. Let's assume that primary weapons are energy weapons, mass drivers/cannons, and missiles/rockets.
  • Energy: A light-second is 300,000 km. Particle weapons would travel much more slowly than C, but for lasers, 300,000 km is probably a reasonable maximum range. Anything longer than that and you'll start to have aiming problems. Note that this is a problem with sensors, too; a radar or lidar pulse needs to travel two ways (out and back), and the maximum unambigious range is likely going to be much less depending on waveforms and whatnot. There are also problems with sensor range due to the formula for a sphere; the returning energy pulse is reduced by a power of 4*PI*R^2 so you need VERY sensitive receivers to detect a returning pulse from extremely distant targets, even without atmospheric attenuation.

    I also imagine that you'd have trouble with dispersal reducing the power level of the beam as it spreads over distance. You'd need a very tight, focused beam and the power will attenuate over distance. The YAL-1, a megawatt class laser, has range of ~600 KM vs. thin skinned targets in an atmosphere. Here's a quick back of the envelope calculation:

    Power Density = Transmitted Power / 4 * Pi * R^2
    Power Density = 1 megawatt / 12.56 * 600 KM^2
    Power Density = 1 megawatt / 4,521,600 KM

    So, I think something on the order of ~1000 KM is reasonable for desired weapons effects with a megawatt-class laser weapon in a vacuum. If you assumed that a sci fi laser would be a giga-watt class system (1000 times more powerful than the YAL-1), then perhaps closer to 20,000 KM as a WAG, although I'm sure an engineer would tell me how far off I am.

    Power Density = Transmitted Power / 4 * Pi * R^2
    1 megawatt / 4,521,600 KM = 1000 megawatts / 12.56 * R^2
    12.56 megawatts / 4,521,600 KM = 1000 megawatts / R^2
    R^2 * 2.7777777777777777777777777777778e-6 = 1000 megawatts
    R^2 = 360000000
    R = 18973
    (Sorry I got lazy and dropped the units... this is a WAG anyways...)

    Likewise, if you went DOWN to a kilowatt laser, then range would shrink to something like 50 KM vs. a thin skinned target.

  • Projectiles: Range is effectively infinite due to Newton's First Law. However, against a maneuvering target, there might be problems with anything at longer ranges. If you assume a mid-case 6G manuevering target, then in one second that target can change velocity by 60 meters/second^2. A bullet usually goes at a velocity on the order of 1500 meters/second; artillery shells are much slower (hundreds of m/s) but we're in the ballpark. If you want to be able to hit a 10 meter sized "kill zone" on a maneuvering target, then your projectile needs to arrive in 1/6 of a second or you need to really be able to guess where it will be. That makes the effective range about 250 meters! That makes sense, though; ~750 feet is the heart of the envelope for a fighter aircraft trying to gun another fighter, which has similar acceleration and size issues; atmospherics don't even really come into it.

    If you're going after a 100 meter vital zone on a 3G target, then your bullet has 3.3 seconds, so max effective range would be ~4000 meters.

  • Missiles: Like mass drivers/projectiles, range is effectively unlimited. In fact, it is greater because a missile (A) accelerates after launch and (B) can correct its course with terminal guidance. The only issue is how long it takes to get to the target, and if it has sufficient maneuvering ability to catch a maneuvering target.
So, really, tactical space combat scales can be smaller than you might think. Hexes as small as 250 meters might make sense! Remember, velocity doesn't matter; the only thing that matters is DELTA V (the difference in velocity between combatants). If you went with a 500 meter hex then you'd get the following:
  • Guns vs. Maneuvering Point Targets: 1 hex range
  • Guns vs. Non-Maneuvering Area Target: 8 hex range
  • Megawatt Class Laser vs. Thin Skin Target: 2000 hex range (effectively infinite)
  • Megawatt Class Laser vs. Medium Skin Target: 1000 hex range (still effectively infinite)
  • Kilowatt Class Laser vs. Thin Skin Target: 100 hex range (still effectively infinite)
  • Kilowatt Class Laser vs. Medium Skin Target: 50 hex range
    Note that if you posit armored targets, or better yet, some sort of energy shields, then you could shrink the ranges significantly, especially for a kilowatt class laser. The YAL-1 takes up an entire 747. I understand that sci-tech will make major strides in a sci-fi setting, but if you're talking about a laser that can sit inside a turret like you see in Star Wars, that's a LOT of miniaturization. So saying that small turret-based weapons are kilowatt class is reasonable. A megawatt class laser might be something like a mining cutting laser or a destroyer (not fighter) class weapon.
  • 1G acceleration over a one minute period of time: ~1 hex delta vee (and this relationship holds fairly steady, so 9Gs = 9 hexes of delta vee)

The last bullet there is actually a good argument for using a 600 meter hex for tactical spaceship combat. It would basically create a 1G acceleration = 1 hex movement direct relationship, which is pretty sweet; it wouldn't really affect the maximum weapons ranges much, except that the guns vs. maneuvering targets is getting a bit optimistic. I can also think of some cool things you could do with a D6 and 600 meter hexes. The 500 meter hex is easier to extrapolate to greater ranges, however, and you could assume there are some inefficiencies in the burn or something that keeps acceleration from being perfect.

Alternatively, you could go with some multiple (2-3G) for the hex, which would lead you to 1200 or 1800 meter hexes. You could just round to 1KM, 1.5KM, or 2KM. That basically reduces movement rates for very rapidly accelerating objects such as guided missiles, but it also reduces movement rates for the typical player-controlled ship. If you think that a 3-5G rated ship is "typical" with 9-10Gs being a peak manned combat vehicle, then using 1800 meter hexes means that the typical ship only moves 1-2 hexes, which may not be very satisfying.

Remember, the key is acceleration capability in a fight, not velocity. Assuming that the combatants are intentionally getting into a fight, then one of them has matched velocity with the other. The aggressor in that case should basically be able to enter the fight with whatever starting relative velocity they want. For example, if they enter the fight with an advantage of +3600 KM/HR, then they'll have a velocity delta of 60,000 m/s, or 100 hexes. So, they'll blow through the engagement and only get one pass, which may be what they want. They'll have to do a long ~10 plus minute burn after blowing through to come around for another run which burns a lot of fuel.

It is much more fuel efficient to basically match velocities and enter the fight with manageable Delta Vee. That way you're not burning a bunch of mass to get up to high speed then burning yet more to rapidly decelerate. So letting the aggressor pick their starting relative Delta Vee advantage makes a lot of sense. In a more reasonable and tactical scenario, the aggressor could enter the engagement with a delta vee of +260 KM/HR, which gives them 10 hexes of movement. They could then make a pass on the victim, do a 9G braking burn, and be drifting along one hex faster than the target for round two of the fight -- a manageable place to be! It is a little more complicated than that because they could apply angular delta vee but still, you could come up with rules of thumb to keep it simple and manageable.

I'm going to stop now before I embarrass myself further. It has been a long time since I took physics. But I think that with some careful thought you can create a pseudo-Newtonian feel to the system fairly easily.

Sunday, October 17, 2010

Correspondences of Seven

I've been coming up with a table of correspondences for the number seven, which is core to "Septimus." This is what I have thus far.
  • Quality of Associated Signs: Each planet is associated with astrological signs as a "ruler." I've extracted the quality (fixed, mutable, or cardinal) of those signs.
  • Elements of Associated Signs: Each planet is associated with astrological signs. I've extracted the element (air, earth, water, fire) of those signs.
  • Humour: Each planet is often aligned with one of the four humours.
  • Roman Deity: Each planet is associated with a Roman deity.
  • Liberal Art: Dante Alleghri (yes, that Dante) associated each planet with a liberal art.
  • Mechanical Art: I've matched up the planets with the mechanical arts.
  • Probitate: I've also matched up each planet with a probitate.
  • Metal: Each planet has an alchemical association to a metal.
  • Primacy of Matter, Mind, and Spirit: Each planet has one of these three over another. For example, "Matter over Mind." You can extract it from the symbol for the planet.




























Variable (Melancholic)


Dante's Virtue





Love & Friendship

Good for Fame


















Roman God








Greek God








Quality: FIXED










Quality: MUTABLE



Element: EARTH




Element: WATER




Element: AIR




Element: FIRE




Primacy (Over)








Primacy (Under)






Primacy (Not Present)






Liberal Art








Mechanical Art





Fabric Making











Most of the linkages are straightforward. I'll explain the ones that aren't directly from the classical sources.

The mechanical arts:
  • Agriculture: Saturn has a clear link to Agriculture. Heck, Saturn's symbol even looks like a scythe. This one is easy.
  • Medicine: The sun is associated with Apollo, the god of the sun. Historically, the sun has been associated with positive, healthful things like the healing arts.
  • Armament: This one wasn't perfect, but I thought a correspondence to Mars was appropriate. Traditionally, Hephaestus was the god of smiths. However, given the martial bent of Mars and the strong association with Fire, Mars is appropriate enough. I would prefer Fire + Earth.
  • Commerce: Mercury is traditionally associated with Mercatura.
  • Hunting: Diana, the huntress, is the patron of hunting. Easy.
  • Fabric Making: Traditionally, Athena is the goddess of weaving. However, she doesn't have a planetary association, although she is sometimes linked to Venus. I ended up linking it to Venus almost by default.
  • Architecture: This, like Fabric Making, was "left over" after I matched up all the other arts with their obvious associations. I paired it with Jupiter as Jupiter is associated with kingship, mind, and matter.
The probitates:
  • Riding: I linked this with Saturn due to the agricultural association. However, the Roman God of horses was Neptune which could lead to a weak linkage with the element of water, which would be a reason to put riding elsewhere.
  • Jousting: Linked with Jupiter. This was a "left over" as well and I dropped it here due to the linkage with kings. I thought about replacing it with Chess (tactics) as well.
  • Climbing: Linked with sun. This was also a weak association, based solely on the idea of vertical ascent. It isn't bad, though, as Helios was known for climbing across the sky in his chariot every day. It would also be appropriate to use "Poetry & Music" here as Apollo was well regarded as a patron of both.
  • Fighting: An easy linkage to Mars.
  • Swimming: I paired this with Venus primarily based on the strong presence of the element water. Venus is the only Phlegmatic planet and has the strongest association with water.
  • Dancing: This was matched with Mercury. Mercury was known for being fleet of foot as well as being very social, which is a nice match with dancing.
  • Shooting: The link between archery and the huntress seems straightforward and natural.