Debug Menu:
Pause the game. Hold L2 and press Left, Circle, Up, Down, Right, Right, Left, Triangle, Up, Down. You should hear a sound if you did the sequence correctly. Unpause and press Select to bring up the debug.

Unlimited lives:
Pause the game and highlight the "Exit" option. Hold L2 and press Up, Up, Down, Right, Triangle, Down.

Invincibility:
Pause the game and highlight the "Exit" option. Hold L2 and press Left, Right, Triangle, Down, Right, Left.

Level select:
Pause the game and highlight the "Exit" option. Hold L2 and press Right, Right, Left, Right, Triangle, Down, Right. Now unpause the game and press Select to choose a new level.

Gex quotes:
Pause the game and highlight the "Exit" option. Hold L2 and press Triangle, Left, Circle, Up, Down. Now unpause the game and press Select to force Gex to make a comment.

Rambling Gex:
Pause the game and highlight the "Exit" option. Hold L2 and press Down, Right, Up, South, Right, Left, Right, Down, Down.

Level times:
Pause the game and highlight the "Exit" option. Hold L2 and press Right, Triangle, Right, Left, Triangle, X. Now unpause the game and return to the Media Dimension. Press Select to view the level statistics or Square for the fastest times.

All Remotes Passcode:
Square, Circle, R1, Triangle, L1 R1, L1, R1, Circle, Circle, R1 Triangle, L1, R1, Circle, L1, Triangle Circle, R1, Triangle, L1, R1, Circle L1, Triangle, Circle, R1, L1.