Here are some cheats and tips for the game 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 you�ll see a new option,
Cheats. Highlight Cheats, and press X. This takes you to a cheat menu
that includes invincibility and unlimited ammo.