This game is also available on 3DO.
press T, S, C, S, T, S, L, L1+R1, Select, Select.
The picture to the right should now be a skull.
Now press T, S, L1, L1, L1, S, T.
Select while pressing T, L1, S.
Release Select and press T, L1, S, T, L1, S. A stage selection
should appear. Use left and right to select your level.