An overview of Tetris randomizers. > The 7-bag has a consistent piece output, making it more predictable. It’s easy to know where in a bag you are, and when a piece you need might come. Because of how predictable this random generator is, it’s actually possible to play forever. Overall it’s a silly system that makes you wonder how it ever became the official randomizer. It's actually why I like that randomizer! I should try out TGM3. Funny part: the illustration for the 7-bag features wrongly-coloured tetrominoes.