Turbo mode:
Select single player mode, enter 2FAST4U as a name, then highlight "OK" and 
press A. When the game begins, the blocks will eventually fall very quickly. 

Turbo CPU mode:
Select single player mode, enter AI2EZ4U? as a name, then highlight "OK" and 
press A. When the game begins, the CPU's blocks will fall very quickly, 
while your blocks will remain at normal speed. 

Music kaleidoscope:
Enter the audio options screen, set the song to "Haluci", and the music mode 
to "Choose". Then, select single player mode, enter HALUCI as a name, 
highlight "OK", and press A. A kaleidoscope will appear in place of the 
game. Note: The Nintendo 64 must be reset to quit this mode. 

Delete line totals and reset Wonders:
Select single player mode, enter O1DERS as a name, then highlight "OK" and 
press A. 

Delete line totals, reset Wonders, erase high scores:
Select single player mode, enter 1N175R4M as a name, then highlight "OK" 
and press A.