Here are a few Tetris cheats
that I have found in my Tetris career:
Change any block into a stick (Tengen's Tetris for the NES
Pause the game, enter up, up, down, down, left, right, left, right, B, A
(the famous Konami
Code), and the currently falling piece will transform into a stick. Unpause the game, and continue play as normal. Works only once per level.
Start at a higher level (Nintendo's Tetris for the NES):
Select a starting level at the level select screen. Hold down the A button and press Start. You will start the game at the level you selected, plus ten levels (selecting level 4 and using this code will start you at level 14).
Any others you can think of, write them here!