Alien Trilogy
Stage Skip:
At the password screen, enter the password GOLVL, followed by a number (for example, enter GOLVL24 and you will go to level 24).Highlight Accept, and press X.
Invincibility and Unlimited Ammo:
At the title screen, highlight Options, then select the Enter Password option. At the password screen, enter the following password: 1GOTP1NK8C1DBOOTSON. Highlight Accept, and press X. The words "Cheats Activated" appear. Return to the main menu and youşll see a new option, Cheats. Highlight Cheats, and press X. This takes you to a cheat menu that includes invincibility and unlimited ammo.
Andretti Racing
Different Colored Cars:
Start a new race and go into the "Begin Career" option. At the "Register," enter the following: Go Bears! (for stock cars) or Go Bruins! (for Formula One cars) Then, at the screen where you select your car, there are ones with different paint jobs and company logos.
Area 51
Kronomorph Mode:
Don't shoot anything except the first three STARR Team members. When you do, you'll be taken to a quick briefing screen, and when the game continues, you'll see the rest of the game in infra-red vision as you assume the role of an alien hunter.
Assault Rigs
Enter these codes during the game, but not while it is paused. Each cheat lasts only for the duration of the level.
All weapons:
Press Left, Right, Left, Left, Right, Left, Right, Right, Up, Down, Up, Up, Down, Up, Down, Down.
Invincibility:
Press Left, X, Left, X, Left, Left, X, Right, X, Right, X, X.