Gex Cheats...
99 Lives
Pause the game. Hold the Right Shift button and tap Down, Right, A, C, Up, Left, A.
Instant Speed
Pause the game. Hold the Right Shift button and tap Left, C, Down, Right, Up, Up, Up, Right, Right. Unpause and you'll have speed power.
Invincibility
Pause the game. Hold the Right Shift button and tap Left, C, Down, Up, Up, C, Left, Right, A, Right.
Level Select
In the map of any stage press pause hold Right shift and press left,c,down,left,right,right,up,right,right.
Lightning
Pause the game. Hold the Right Shift button and tap Left, C, Down, Right, Right, Left.
Spit Fire/Ice
Pause game,hold down left shift and Enter: left, C, down, right, right, left.
Super Jump
Pause the game. Hold the Right shift button and tap Left, C, Down, Right, Up, B, B, Right, Right.