Tetris

Cheats

Have access to the most difficult levels
  Turn on the GB, hold DOWN and keep pressing START until the Options screen
  appears. Select the type of game (A or B) e select the level. Next to the
  selected level will appear a heart. It indicate that the level is 10 levels
  up (if you choose level 10 you will be playing in level 20)

Cheats von Camilo (camilolc@uol.com.br)

More difficult level:  Choose Level 9 and hold A, then press Start

Files

For the PC version

1. File:Siztev1trn1-trainer.rar - Freeze new Block (for v1.1)
2. File:Pztev11trn2-trainer.rar - Freeze Falling Tetrimino, No Level/Dificulty Increase (for v1.1)

For the Nintendo Gameboy version

1. File:Tetris faq.txt

For the Nintendo version

1. File:Tetris solution.txt