Medival isn't so dumb, dear. Just read some my ideas:
Humans Team:
Weapons:
Lot of throwing stuff - axes, spears, knifes, shurikens (!) etc - lot of damage, small amount of ammo.
Shooting stuff: crossbow, bow.
Melee weapons: swords, and throwing stuff would be useful too.
Alternate weapon: miserycord.
Armors:
Light Armor: chainmail.
Helmet

: helmet.

Battlesuit

: full armor.
Buildings:
Reactor

: Christian altar.
Armory

: Blacksmith workshop.
Medistation

: small baptismal font.
Defence Computer

: book shelf.
MG Turret

: ballista, sth like that.
Tesla Coil

: no idea, some kind of ballista, or sth like that

Repeater

: small Christian altar.
Items:
Shield would be useful. While shielding no possiblity of attack.
Grenade

: some kind of medieval bomb, or sth like that.
Medkit: small vial with holy water.
Battery pack

: quiver.
Jetpack: Black ninja cape - disallows flying, allows wallwalk.
Aliens:
More spiderous. Less HP. Bit slowlier.
No barbs for advanced dragoon. No electrical shock for

advanced marauder.
Advanced dragoon and advanced marauder can flamethrow, like drakes.
And trapper allow more movement. No bigger changes.