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.
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.