What are the effects of the various sorts of combat (firefight, melee, etc) in gravities other than the standard 1g?

I'm talking about both higher and lower gravity, as well as microgravity. What games make an attempt to model the effects?

Cyberpunk had a sourcebook detailing this. Eclipse Phase has it in the base rules. A Time of War, the BattleTech RPG has this too. I don't know GURPS that well, but an associate of mine loves it and says the GURPS rules are better (at everything, if you listen to him tell it).

Index Card rpg, kind of, various critters and suits can 'walk on any surface' very helpful in low to zero g.

the rest would be just seat of the GMs pants.  hey its OSR....

I think, generally, the GURPS rules are a bit too fiddly with all the Gee Tollerance and Gee Experience advantages and skills.

Overall, I'd have high gravity cut ballistic weapon ranges to 3/4, bipedal movement rates to 1/2.  Vehicle loads would basically double so the acceleration would be halved but the top speed would probably be the same.  Falling damage is doubled.  Acrobatics is attempted with heavy encumbrance.

In light gravity moving more than half speed risks loss of control. Ballistic weapon ranges might be 50% greater though there's probably a learning curve getting used to it.  Traction is generally poor.  Dust clouds are easier to raise and stick around longer.  Falling damage is halved.  Acrobatics are harder until you get used to the gravity and then easier.

In zero gravity, if you lose control while moving, you probably don't come back down.  Ballistic ranges are unlimited and direct fire only.  Falling damage doesn't really exist but you can really slam into things in any direction, jump too hard and you'll hit your head on the roof.  Acrobatics are tricky as many of them involve landing and you won't be doing that here.

I'd simplify it to addition range penalties for ballistics until you have trained in that particular gravity well or have sighted your weapon in.  Of course, some folks already train for that like snipers or they have ballistic computers to calculate the offsets.  Any 'smart' gun probably can measure and calculate trajectories on the fly.

Here's the kind of thing I'm wondering about. You're having a brawl in 1/3g.

How much of the force of blows actually causes harm, and how much is turned into motive force instead? How does that affect being able to stay grounded (magnetic boots would be vital, assuming you're on a deck)?

What differences would acclimation to different gravities insert into things? In the above you have one combatant who's from 1g fighting someone who's from 1/3g. They're going to be stronger and probably more durable. Would they be tossing the other person around with ease?

For zero g/ micro gravity, I usually just worry about whether they are wearing magnetic boots (half speed, no running, but can shoot and fight more easily) or floating along (risk of spinning out of control from combat)

That's about as complicated as I want to get

As luck would have it... running a zero-G encounter in a ship section with a massive hull breach. 

One of the issues I am wrestling with is the effect of firing a weapon in zero G.  Like how much push back would there be? Can it be used for propulsion?

As is some of them have powers to teleport and others have rocket packs on their armor so... should add a fun dimension as well.

Classic Traveller has rules for this baked into the combat system.

Quote from: Johnny Utah on April 25, 2025, 10:45:11 AMFor zero g/ micro gravity, I usually just worry about whether they are wearing magnetic boots (half speed, no running, but can shoot and fight more easily) or floating along (risk of spinning out of control from combat)

That's about as complicated as I want to get

It's the in between where I think it matters. Not either full Earth-like gravity or zero, but less than. Or more than. If you're on a smaller planet/asteroid, or station spun up to less than a full g, or a ship under lower thrust.

Quote from: Captain_Pazuzu on April 26, 2025, 02:58:58 AMAs luck would have it... running a zero-G encounter in a ship section with a massive hull breach. 

One of the issues I am wrestling with is the effect of firing a weapon in zero G.  Like how much push back would there be? Can it be used for propulsion?

As is some of them have powers to teleport and others have rocket packs on their armor so... should add a fun dimension as well.

If it's a weapon that uses a propellant of some sort, it's a miniature rocket. So you'd need to be braced (or have counter-thrust) not to invoke Newton's Third Law. So yes, it can be used for propulsion/maneuvering.

That's why some sci-fi settings also have recoil-less guns, often they're mini rocket launchers that don't engage any sort of thrust until they've left the barrel.

Quote from: jeff37923 on April 26, 2025, 03:15:11 AMClassic Traveller has rules for this baked into the combat system.

Tell me more. Does it account for things like combatants who have skeletons/musculatures from different native gravities?

Quote from: Kiero on April 27, 2025, 07:03:20 AM

Quote from: jeff37923 on April 26, 2025, 03:15:11 AMClassic Traveller has rules for this baked into the combat system.

Tell me more. Does it account for things like combatants who have skeletons/musculatures from different native gravities?

Yes. In CT, your Endurance score was the number of times you can swing a melee weapon which is adjusted by the weight caused by local gravity (or lack thereof). Gun combat has different recoils for each weapon which can effect your accuracy or stability in Zero-G. Bow weapons are an interesting corner case since they combine both.

Quote from: jeff37923 on April 27, 2025, 09:19:03 PMYes. In CT, your Endurance score was the number of times you can swing a melee weapon which is adjusted by the weight caused by local gravity (or lack thereof). Gun combat has different recoils for each weapon which can effect your accuracy or stability in Zero-G. Bow weapons are an interesting corner case since they combine both.

Is your Endurance (and whatever strength-analogue) impacted by the gravity the character grew up in?

What I'm getting at is there's not just the local gravity things are taking place in, but the adaptation of the combatants as well.

Quote from: Kiero on April 28, 2025, 04:12:46 AM

Quote from: jeff37923 on April 27, 2025, 09:19:03 PMYes. In CT, your Endurance score was the number of times you can swing a melee weapon which is adjusted by the weight caused by local gravity (or lack thereof). Gun combat has different recoils for each weapon which can effect your accuracy or stability in Zero-G. Bow weapons are an interesting corner case since they combine both.

Is your Endurance (and whatever strength-analogue) impacted by the gravity the character grew up in?

What I'm getting at is there's not just the local gravity things are taking place in, but the adaptation of the combatants as well.

It can be. That was covered in later books and versions of the game.


Once Endurance runs out in combat, there is a negative modifier to hit. There is also combat drugs and physical training that characters can undergo to increase their physical characteristics.