Load the game with the "-debug" command line parameter. Then while playing as the indicated character, press ~ and enter one of the following case-sensitive codes to activate the corresponding cheat function. Note: Enabling cheats will disable saving the game.
Load species
Start the game with the "-debug -l[ampcxtr]" command line parameter, where a is the alien, m is the marine, p is the predator, c is the civilian, x is the xenoborg, t is the praetorian alien, and r is the predator-alien. Note: All letters are case-sensitive.