Invincibility
Enter LVFRVRDD as a password. You will then be able to start from the beginning, or enter a level code.
Level Passwords
Level 2: FGHTRMNS
Level 3: HSDSHSBS
Level 4: MXNMSNNG
Level 5: THXBXSCK
Level 6: NNTNDWNY
View Ending Movie
Enter NFNTMMDD as a password.