need i say more...
Ok but we have a choice
1 .Aliens vs Predators
2. Aliens vs USCM
3. USCM vs Predators.
(USCM is the Marines (which i dont think i can spell right))
And if you can get the ailen life cycle to work +30 to you

The USCM is easy. You just re-skin the humans and sounds. (maybe tweak the guns a bit)
Weapons.
Pistol.
Rifle.
combat knife.
Mg with nade launcher.
Shotgun.
Smartgun (if you can impliment semi homing ability use that(plus stronger but eats ammo like a fat guy at mcdonalds) no homing (just very strong)
C-4(need i say more)
Buildings
Auto guns. replaces

(if you can have the ammo display thing so u have to reload em periodicly then cool

)
Landning Beacon (replaces

)
Communications post (replaces

)
Remote radio terminal (replaces

)
Weapons rack (replaces

)
first aid box. (replaces

)
leaving all else as-is
Predators... now then this might be tricky if its preds v humans any ideas?

Guns is simple
Hand to hand
Talons
Spear
Plasma caster
disc
speargun
Netgun (similar effect to trapper)
if it were Aliens V Preds then just re-do the humans.
Aliens.
All aliens can climb walls (barring those marked with a *)
attacks may include
(LMB=claws RMB=tail MMB=inner jaws)
Facehugger. (if you can have it forced to evolve to next class then good if not hen we just start out straight from the next one)
Chestburster. (like a dretch but WEAKER and SLOWER)
Drone. (builder)
Warrior. (stronger than builder but cannot build)
Runner. (faster than warrior but weaker)
Preatorian. (bit stronger than Warrior but evolutionary prequsite)
*Ravager. (Big guy with huge blades on his arms (2 evos)
*Sentinal. (Acid Spitting hive defender slow but powerful (2 Evos)
*Queen. (very powerful but lacks claw attack (tail can kill in one hit if human doesn't have armour) claw attack is replaced with lay an egg (3 evos)
Buildings. (there will be very few due to aliens nature but here is how it might go)
Main hive node. (replaces

)
hive node. (acts more like

because it doesnt spawn units (sprays acid as cheaper form of defence)
Egg. (wont spread creep)
Stillborn egg. (some facehuggers embryos die as they leave the host these are those eggs (these are expensive slow firing (yet very effective) defences)
i'll leave you to decide the costs of bulidings cos if it were up to me id set it all to 1 for thefun of it.
Its just a mod for fun im not asking for all 3 races just two of them and if it is just a simple reskinning and resounding then ill be happy:)
Please Please Please don't flame