Turok 3: Shadow of Oblivion

Enter these at the secret screen for the desired effect.

Enter [Jaguar] [Horse] [Elk] [Fish] [Jaguar] [Hawk] as a password at the "New Secret" screen.

Successfully complete the game as either Danielle or as Joseph (possibly under the Oblivion difficulty setting). Go through the credits until a cheat is revealed, then save the game. Immediately start a new game with the other character (also on the Oblivion difficulty setting) and complete it. Watch the credits again and get the cheat. Check your secrets screen, and you can now play as Joshua. Joshua gets all weapons (fireswarm and shredder firestorm cannon and sniper rifles, etc.)

Complete Joseph and Danielles quest on the same game note to unlock this mode. Joshua can have both upgrades of each weapon when he collects one, instead of just one. (When you complete a game, start a new one with the other character, then save the note)

Enter [Horse] [Eagle] [Snake] [Cougar] [Insect] [Salmon] as a password at the "New Secret" screen. All enemies will be twig-like in a single player game.

Enter [Elk] [Lizard] [Dragonfly] [Lizard] [Hawk] [Owl] as a password at the "New Secret" screen. Then enter [Horse] [Bull] [Wolf] [Raven] [Eagle] [Rabbit] as a password. Almost the all cheats will be unlocked.

Enter [Frog] [Frog] [Salmon] [Insect] [Wolf] [Cougar] as a password at the "New Secret" screen. . All enemies will be smaller in a single player game.

Enter [Salmon] [Elk] [Bull] [Snake] [Eagle] [Salmon] as a password at the "New Secret" screen.

Enter [Elk] [Elk] [Elk] [Elk] [Elk] [Elk] as a password at the "New Secret" screen.