Lancer's multi-player skin:
Enter the "Extra" menu and enter "YLLWFLLW" as a code.

Level select:
Enter the "Extra" menu and enter "RECLAMATION" as a code.

Rand's multi-player skin:
Enter the "Extra" menu and enter "KIDGLOVES" as a code.

Rook's multi-player skin:
Enter the "Extra" menu and enter "BLUEANGLS" as a code.

Scott Bernard's multi-player skin:
Enter the "Extra" menu and enter "LTNTCMDR" as a code.

Defeating larger enemies:
When fighting the bigger enemies, aim for the eyes.

Invincibility:
Enter the "Extra" menu and enter "SUPERCYC" as a code.

Infinite ammunition:
Enter the "Extra" menu and enter "TRGRHPY" as a code.

One-hit kills:
Enter the "Extra" menu and enter "DUSTYAYRES" as a code.