"Hold that Fuji!" cheat mode:
Hold Pause + Option and keep them pressed during the entire code. Press 1+ 3. Then, press 2 + 5 + 7 + 9. The Predator will laugh to confirm correct code entry. The following codes may now be activated.

Security clearance
Press Option + 6 to raise or Option + 9 to lower.

Toggle motion tracker
Press Option + 8.

Recharge all weapons
Press Option + 1 + 2 + 3 + 4.

Toggle shotgun
Press Option + 1.

Toggle pulse rifle
Press Option + 2.

Toggle flame thrower
Press Option + 3.

Toggle smart gun
Press Option + 4.

"Banana Stops" cheat mode:
Press Pause, Option, 6, 1 + 3, then release those buttons. Then, press B, A, 9, A, 9, A, *, Option, 6, #, *, *, Option, 2, Option. The Predator will laugh to confirm correct code entry. In addition to the "Hold that Fuji!" codes, the following codes may also be activated.

Level select
Press Option + A to jump to the next level or Option + B to play the previous level.

God mode
Press Option + 5 for invincibility and full weapons.

Shotgun (as Marine)
Press Option + 1.

M14-A Pulse Rifle (as Marine)
Press Option + 2.

Flame Thrower (as Marine)
Press Option + 3.

Smart Gun (as Marine)
Press Option + 4.

Refill Ammo (as Marine)
Press Option + 1 + 2 + 3 + 4.

Motion Tracker (as Marine)
Press Option + 8.

Raise Security Level (as Marine)
Press Option + 6.

Lower Security Level (as Marine)
Press Option + 9.

Combi Stick (as Predator)
Press Option + 1.

Shoulder Cannon (as Predator)
Press Option + 2.

Smart Disc (as Predator)
Press Option + 3.

Wrist Blade (as Predator)
Press Option + 4.

Tail Attack (as Alien)
Press Option + 1.

Claw Attack (as Alien)
Press Option + 2.

Extending Mouth (as Alien)
Press Option + 3.

View quick Alien ending:
Enable the "Banana Stops" cheat mode. Create a cocoon and allow the alien to be killed after it matures. Press Option + A or Option + B as the cocoon is hatching to view the ending.

Freeze Alien Queen:
Save the game just outside the Queen's Lair. Load the saved game. The Queen may now be damaged. She may be killed after walking through the entrance to unfreeze her.

Display coordinates:
Hold Pause and press Option, 1 + 3, Option. The sound of the shotgun will confirm correct code entry. The following information will appear: dec(xx,yy) x/y coordinates, hex(nnnn,nnnn) precise hexadecimal coordinates, and 1(nn) level number.

Hints when playing as the marine:

To get access 2 and 3 you must use the vents.

Do not bother with access 4, because access 5 is just sitting in a corner of sub-level 5. It is near the escape pod airlock.

Access 6 is in the med-lab on level 4 (?). To get in, you must use air duct 4c.

Access 9 and the smart gun are on the predator ship.