Cheats:

 Procedure:

 Press [P] when playing to pause the game.
 Press [Enter].
 Write the cheat code (within 3 seconds).
 Press [Enter] again.

 FISK    - Full Shield
 TRAN    - Extra life
 1501    - More money   (repeat to get a lot)
 ARGH    - Autofire     (repeat this one too)