Level select
Enter "FREEPLAY" as a password.

Invincibility
Enter "NODIE" as a password.

All weapons
Enter "GIMME" as a password.

Invisibility
Enter "NOSEEUM" as a password.

Mini mode
Enter "SHORTY" as a password.

Big mode
Enter "IMHUGE" as a password.

Debug information
Enter "THDOTEST" as a password.