Codes acquired from codes.ign.com
Tetris



Harder Game
At the title screen, hold DOWN and press START. When you start your game 
you will see a little heart by the level and the game will run much faster.
submitted by Benjamin Katt

Helpful Hint
You know that those blocks and l shapes can be pretty annoying. Well right 
from the start make a column on the left hand side for blocks only, then 
another column for l shaped only. When you need them use them in the center 
but otherwise do as I said.
submitted by Chris Pateman 

No Preview
To play a harder game where the next piece is not shown, hit START during 
any point of the game. While the game is paused, hit SELECT. When the game 
is restored, the box where the next piece is shown will be empty. To show 
the pieces again, repeat this process.
submitted by rghanson@iamerica.net

Secret Ending
In Tetris mode B there is a special level ending. To earn it score 25 lines 
on level 9, with the initial height set to 5. If you're successful you will 
be rewarded with new music with Russian dancers and musicians prancing in 
front of the title picture.
submitted by Kenny Coats

Secret Rockets
Secret rockets are found in both type games. The type A game will show a small 
rocket when you hit 100,000 points and a large rocket when you hit 200,000 
points. The type B game shows a space shuttle taking off when you beat the game 
at level 9 and height 5.
submitted by Bathazar (duncana@ix.netcom.com)