Level select -
Hold [Shift] + [Ctrl] and click on "Single Player" to play any normal or special 
level in the game.

Cheat Codes -
While playing a game, enter one of the following codes then press [Enter] to 
activate the corresponding cheat function. Note: If colonists are selected, they 
may follow the command assigned to various keys being entered in the code.

Result - Cheat Code
Level skip - gsawin 
Heal all colonists - gsaheal 
Removes all roofs - gsaroof 
Control aliens - gsaswap 
Kills selected characters; use with gsaswap code to kill aliens - gsakill 
Stops aliens and colonists - gsastop 
BOG weapon created at pointer; collect it for extra defense and ability to lock 
doors - gsabog 
KNIFE weapon created at pointer; collect it for invisibility to aliens - 
gsaknife 
Commander created at pointer - gsacmdr 
Medical officer created at pointer - gsamedi 
Technician created at pointer - gsaboff