Here are the cheat key sequences. To use one, type in the sequence
of keys while the game is in play. Once a cheat is used, the player's
score is no longer kept and is not eligible for the high score list.
  
Code    Effect
--------------------------------
fix   - Repair all your ships to 100%.
fry   - Immediately destroy all enemies.
bake  - Make all of your ships invulnerable.
kat   - Skip current mission to next mission.