Cheat Mode
Enter these on the designated password screen from the Main Menu:
VGKKNXUK - All Weapons
AAUGSZZA - Extra Lifes
SZNUIYVG - Infinite Lifes
SXSTYNVK - Sustain no damage from bullets
VTNZXVVK - Sustain no damage from spikes
Hints
Unlock Ranks
To see your rank, on the Main Menu, Q*Bert will be standing on a cube with a number on it. That number is your rank. If you're rank 1, you can't step on any "special" cubes. If you're rank 2, you can step on cubes with a 2 on them. If you're rank 3, you can step on cubes with a 3 on them. You begin with rank 1.
Rank 2 - Get a score of 60,000+
Rank 3 - Get a score of 100,000+