Passwords:

To enter the passwords, select "Resume" from the title screen, then input the desired password.

Password - Effect:

TC1LE - Fifth Checkpoint
TC1LE9H - Final Checkpoint
T - First Checkpoint
TC1L - Fourth Checkpoint
TC - Second Checkpoint
TC1LE9 - Sixth Checkpoint
TC1 - Third Checkpoint

Skip to final level

Enter the following in the main password screen off the main menu.

Password - Effect:

TURTLE - Skip to final level