New Tetris (N64)

Kaleidoscope:
Go to the options screen and change the song to Haluci and the music mode to Choose.Now start a single player mode and put in HALUCI as the name, highlight OK and press A to start.

Get Fast Mode:
(submitted by: Brian Holt)
Enter 2FAST4U as your name.

Better AI:
Enter AI2EZ4U as your name.

Auto Win (single player):
During any game, press start and enter: C-Left, C-Left, C-Right, C-Right, C-Up, C-Down, R, R, L, L, hold Z and press start.

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.