Enable cheat menu:
Pause the game by pressing start, then press C-Up, C-Down, C-Left, C-Right. A cheat option will appear at the bottom of the menu. The following cheats will be confirmed by a whooshing type noise when you enter them All artifacts:
Enter the cheat menu and press C-Up, C-Right, C-Down, C-Up. Enter the collect menu to activate the code. All keys:
Enter the cheat menu and press C-Down, C-Up, C-Left, C-Right. Enter the collect menu to activate the code. All puzzle items:
Enter the cheat menu and press C-Up, C-Left(x3), C-Right, C-Down(x2). Enter the collect menu to activate the code. All weapons:
Enter the cheat menu and press C-Right, C-Up, C-Down(x2). Enter the collect menu to activate the code. Full health:
Enter the cheat menu and press C-Left, C-Up, C-Down(x2). Invincibility:
Enter the cheat menu and press C-Left, C-Right, C-Down. Kill all visible enemies:
Enter the cheat menu and press C-Down, C-Up, C-Left(x2). Level select:
Enter the cheat menu and press C-Left(x2), C-Right(x2), C-Down, C-Top. Walk through walls:
Enter the cheat menu and press C-Up(x20), C-Down.