Rampage: World Tour cheats and cheat codes for Nintendo 64

Level selection:
Go to the character selection screen and press the following button 
combination: Hold L + C-Up + C-Down + C-Left + C-Right then start a 
new game. After, hit Down or Up to choose a country or Right or Left 
to choose a city at the "Peoria Day 1" screen. 

Unlock Tyrannosaurus Rex
Complete all levels, after begin a new game. Highlight Lizzy at the 
character selection screen. Then, hold Z and press L, R several times.
If the code is accepted you should hear a scream.

Change colors
Highlight Lizzy or George or Ralph at the character selection screen. 
After selected a character, hit Up.

Play as V.E.R.N.
If you play on Scum Lab facility stage, eat some toxic waste 

Jump 7-10 days forward in the game:
Wait until the actual stage is over and city name appears
on the screen. Then before the city name disappears, 
press the indicated actions with your character:

George:
Press Jump, Punch, Kick

Lizzy:
Press Punch, Kick, Jump

Ralph:
Press Kick, Jump, Punch