Roby from Italy asked my advice on Sci-FI Crossfire. I’m no expert on science fiction but here’s some ideas …
It really depends on your genre but to quote Paul Ward “any changes are done via force organisations and firing dice”.

For each type of squad/vehicle/etc assign …
- Armour: go for the standard CF of using different mechanisms for anti-personnel fire versus anti-armour; or give Armoured targets cover benefits like entrenchment and/or bunker
- Direct Fire Anti-Personnel capability: e.g. like a Rifle Squad, or SMG squad, or HMG, Direct Fire Gun with HE
- Direct Fire Anti-Armour capability: e.g. ACC in range -1 to +1 and PEN in range -3 to +3. Is everything armoured as you can ignore it for game purposes and just use anti-personnel mechanics?
- Indirect Fire Capability: e.g. Firing dice; Number of Fire Missions (FM); does it need a FO to direct fire or is this handled by satellite etc?
- Arc of Fire: e.g. like a squad or HMG
- Number of firing dice: must be in the range 2d6 to 5d6. The standard squad should get 3d6. Potent weapon systems should get 5d6. Particularly weak shooting ability should get 2d6.
- Number of attacks: e.g. I give tanks a main gun and machine gun which fire separately and can combine in a fire group. This makes tanks very potent compared to standard CF
- Number of move actions per initiative: either 1-3 moves actions or unlimited
- Movement style: ground and/or air
- Morale: Green, Regular, Veteran
- Close combat bonus: 0, +1, +2 on top of moral bonus
- Command and Control: Good, Okay, Poor, or not applicable (for things that don’t rally like tanks in normal Crossfire)
- Size: is anything big enough to be seen over and see over terrain that normally blocks LOS? This is a very dangerous tweak for CF. Woods and Hill should always block. Houses probably should. Fields might not block a Battle Mech. What happens if a big armoured thing enters a building?
So, for example, in a genre where everything is armoured …
- Battle mech: Veteran, Armoured (counts as bunker), Direct fire main gun 5d, Direct Fire secondary gun 4d6, squad arc of fire, Indirect Fire 4d6 10 FM no FO required ; Good (German) Command & Control ; +1 close combat (and veteran)
- Ground troops squad: Green, direct fire 3d6, Poor (Russian) command and control, squad arc of fire
- Ground troops heavy weapons: Green, direct fire 4d6, Poor (Russian) command and control, heavy weapons arc of fire
This battle mech would kill a lot of ground troops.
You’ll need rules for flying and/or air support.