Cheat: Level Passwords
At the Password screen, enter these codes to unlock different stages:

2: PBBQBB
3: QBCQBB
4: SBFQBB
5: DBKQBB
6: NBTQBB
7: PCTQBB
8: RFTQBB
9: CKTQBB
10: MTTQBB

Cheat: Level Select
To enable level select, go to the Passwords screen and enter this code: NTTTTT.


Unlockable: Hidden Art
To unlock hidden concept art, enter MFKRPH at the Password screen.