Crystal Caves

God Mode....... Z-E-U-S (with god mode on, 'G' will toggle 
                         gravity) 
Warp Mode...... N-E-X-T 
Increase Ammo.. X-T-R-A

NOTES: For 'warp mode' and 'increase ammo' you must release 
the third key of the four-key combination before you release 
the other keys.

EXAMPLE (warp mode):

First, press and hold: N E X T 
Next, release: X
Then, release the other three keys.