Enemy Infestation Cheats

gsakill - Kills selected characters (your own, or swaps, selects, and kills aliens).
gsastop - Stops both aliens and colonists from acting, causing them to just stand around; type it again to toggle it off.

More Weapons:
gsabog - Creates a BOG weapon at the cursor that when you pick it up gives you extra defense and lets you lock doors.
gsaknife - Creates a KNIFE weapon at the cursor that when you pick it up makes you invisible to aliens (they won't go for you when they would normally see you).

More guys:
gsacmdr - Creates a commander at the cursor.
gsamedi - Creates a medical officer at the cursor.
gsaboff - Creates a technician (boffin) at the cursor.

Win and move on:
gsawin - Wins the level no matter what (so you can continue to the next).