Enter the following cheats at the "Enter Cheat Code" screen:
NTHGTHDGDCRTDTRK=THE BIG CHEAT It means "On the eigth day God created Turok" Without the vowels and the "Y" This cheat accesses you to Infinite lives, All map, Invincibility, Spirit mode, Unlimited ammo, Big head sesh, All weapons, Level warps, and Boss warps.
LLTHCLRSFTHRNB=Purdy Mode makes everything colorful and purdy.
DNCHN=Dana Mode is a mode that makes your enemies small but not defenseless. Also it shows the credits.
NSTHMNDNT=Show enemies is where enemies show up on your map, this is good for going around corners.
DLKTDR=Pen and ink mode, this mode is a crappy version of Turok it is in black and white and is hard to navigate in.
THSSLKSCL=Spirit mode, gives you Invincibility, and you enemies move in slow motion.
FDTHMGS=Credits without having to beat the game.
THBST=Gallery, before you start the game enter this cheat and you can rotate your enemies in all directions.
SNFFRR=Disco mode, is a mode that is like spirit mode except only the lights flash.
RBNSMTH=Robin's cheat, this cheat gives you Invincibility, credits, big head sesh, unlimited ammo, and of course all weapons.
GRGCHN=Greg mode, this gives you all weapons, unlimited ammo, big head sesh, and the credits.