At the difficulty selection screen, press [Tab] + [Ctrl]. Then type: ROBISAGOD to enable cheat mode. To activate a cheat, enter its corresponding code below.

Cheat                           Code
All weapons                     KICKASS
Blood mode                      GIVEBLOOD
Invincibility                   BEAGLE
Level skip                      GETMEOUT
Rescue all hostages             RESCUE
Reveal hidden areas             INFRARED
View end sequence               GEEWHIZ

To play as Agent Squiggly, press [UP] at the player selection screen. Then type: SQUIGGLY.