AD&D is a far end of the spectrum in that it has far too many rules to keep it simple. You need a college degree (well, maybe a minor) in D&D to run it properly. 3.5 and many other games use iterative one-after-the-another initiative which is a "silent killer."
The following thoughts are my attempt to keep the best of all worlds. Each round is divided into three phases: Fight, Move, and Communicate. I've done some tactical work and those are the three things you need to be effective on a battlefield (well, really it is shoot instead of fight, but hey, close enough), and those are the things that should be happening regularly in combat, so that's what our system will care about.
At the start of the round, we check initiative and then generally go in an "us and them" fashion each phase as such (assuming A wins initiative):
FIGHT -- Side A
FIGHT -- Side B
MOVE -- Side A
MOVE -- Side B
COMMUNICATE -- Side A
COMMUNICATE -- Side B
If there are three or more factions then just extrapolate. The key is that everyone resolves a phase before moving on. Very few things will break our "sequencing."
Each character gets one simple action per phase. They generally get to upgrade one simple action to a complex action each round. A simple action involves precalculated, rapidly used scores. There are no situational modifiers (unless they apply to the whole side) nor are there any random dice tossed. Complex actions involve situational modifiers and randomized dice throwing. Thus, players will need to decide in which phase they want to use their complex action.
Characters have a derived proficiency score for each key action. For example, in the fight phase, we have:
- Shoot (Range)
If using a dice pool system, the proficiency score is the size of dice in the pool, capped at 6; the pool has to get to 21 dice to get a simple score of 7 (unlikely to say the least). If using a D20 system, it should be a fixed number representing a somewhat less than average roll (for example, 7+THAC0 level-based to-hit bonus). I'll use my dice pool system (which has Target Numbers from 3 to 8 for the most part, for reference's sake) in further examples.
So, our character -- let's say he's a swashbuckler -- might have Melee 3, Shoot 2, Dodge 3. If taking a simple action, he can automatically hit anything with an AC or Target Number of 3 using his melee attack. He misses if it is 4 or higher. So, our swashbuckler can skewer rats or zombies all day, similar to the "fighter sweep" of yore. This frees up his complex action for rapid movement or lots of special communication.
However, say, he's up against a nimble, worthy opponent, like, say, an unusually aggressive lion. Hitting TN 3 won't cut it. In this case, he uses a complex action. Instead of just taking a "3," he gets to roll 3d6 and retain the highest (using my core mechanic). On average he'll hit around TN 4.75 or so, with a possibility to hit TN 8! The player can even argue for a situational bonus, perhaps due to terrain or some other circumstances.
Of course, if he uses his "complex action" in the fight phase, then when we get to movement, he's relatively anchored. He's stuck with moving two or three hexes -- whatever his simple move score is -- instead of rolling 2d6 or 3d6 to move several more.
The communicate phase encompasses all other actions. Rallying followers, giving orders to mooks, casting spells, using many other skills, and so on.
Wrinkle: Free Dice. As a wrinkle, each player begins an encounter with one "Free Die." This die may be added to any active die roll, or it can increase a simple score by one. If a player ends a round without using a complex action, they gain one free die. If they end a phase without spending a simple action, there is a 1/6 chance they gain a free die. Players may not accumulate more free dice than some number between 1 and 7 (tied to an attribute or something). The DM also gets free dice, and furthermore, he can share them freely among monsters to minimize bookkeeping.
Wrinkle: Extra Action. You could occasionally grant extra complex actions. This is a pretty sizable boon. Of course, you don't get extra dice. The character can spend both complex actions in the same round but must split his available dice however he wishes. I'm still thinking this through, and wondering if the extra action should only translate to a simple action (thus, you could have a Complex & a Simple action in the same phase, or two complex actions in two different phases).
Wrinkle: Minions & Actions. Minions don't often get to take complex actions. Instead, they can either take a simple action or they can lend their dice to another's pool, encouraging them to gang up on foes. Some "leader" type monsters may grant an action to a nearby minion, which then makes the players decide whether they need to take out the leader (to cut off the actions) or take out minions (easier to kill, rapidly reduces the dice thrown at them each round and reduces the odds of a hit). Bodyguards for players and other such NPCs work the same way.
EFFECTS & VARIATIONS
This system has several effects. First, it forces players to dynamically allocate limited resources. Each round they must decide where to take their complex action. They must also manage free dice, and decide when it is best to sit tight, do nothing, and take a breather (to get more free dice) and when to go for broke.
This also evens out "screen time." Calculating situational modifiers, rolling dice, and then evaluating the results are by far more time consuming. This is a common complaint for many fighter types in OD&D and AD&D; they get to roll one d20 and if they hit they get to roll damage, once per round. Meanwhile, clerics are chucking 2d6 to turn undead, mages are throwing fireballs for fistfuls of D6 of damage, and in general it feels like everyone else is rolling more dice. With this system everyone gets about the same number of random rolls to play with each round, regardless of how good they are at a specific task.
We get rid of most of the need for AD&D's rules about weapon length, ranged attacks, etc. The "fight" phase goes first, so if you aren't in melee when the round begins, you pretty clearly don't get a chance to strike unless you have a ranged weapon handy, unless we implement some sort of "charge" action in the move phase, or unless we have some sort of rules for readying or holding actions in reserve "out of phase." A really simple one would be, "You can take an inappropriate action during a phase, however, it must be fueled by free dice." Another would be allowing common sense "readied" actions (for example, readying to receive a charge by striking however runs in, or readying to swat someone if they try to cast a spell). If your action never triggers at least you get the comfort of building up your free dice pool.
I think it would be interesting to present different options to players. For example, you could play one of these three variants:
- All proactively used simple scores (and thus all dice pools for active rolls) are increased by one, all the time.
- You get (A) one extra simple action or (B) may upgrade one simple action to a complex one, every round.
- All reactively used simple scores -- such as Dodge -- are increased by one, all the time. This also increases dice pools when using these skills actively, as when one is doing a "full round dodge."