This is a question I've had since I first played this game, maybe twenty years ago. I would say that it is random, given the nature of the game. However in my experience; the O-blocks never come alone (after you get one, the chance of getting another seems more likely). I also feel that you get the I tetromino just after you made a mistake.

I've been googling this for quite some time and haven't found a conclusive answer. Can somebody please help me? I've only played the game on the original Gameboy.

  • 3
    The perception of getting multiple O blocks in a row or getting I after making a mistake is probably confirmation bias - these situations are annoying, so you notice when they happen. (Unless you're playing Bastet)
    – Random832
    Apr 9, 2012 at 12:40
  • In the version I've played most the ---- block is much less frequent than the others, which makes it impossible to play perfectly. Very annoying. Apr 9, 2012 at 20:06
  • For what it's worth, once when playing on a PC back in the day, I got a run where it gave me two ---- blocks, followed by another piece, then two more ---- blocks... It was at the highest speed setting. I think I eventually got bored and quit. Must've been a weird fluke in the programming.
    – Kyralessa
    Apr 9, 2012 at 23:47
  • 4
    As a species, we are notorious for spotting patterns where none exist. If you do some googling, you can find plenty of examples of people convinced that random events in games (especially online poker) are biased against them, or that popular and well-studied random number generators do not work correctly. There is a long SO thread, Need for predictable random generator, that discusses this issue, with examples of not-quite-random generators used in games, that seem 'fairer' than the real thing.
    – James
    Apr 10, 2012 at 12:37
  • I'm aware of the human nature in this context. I was just wondering about maybe in this case I was right or not. Apr 10, 2012 at 13:34

2 Answers 2


This is kind of a vague question and the primary answer is going to be equally vague: it depends on which Tetris you are playing.

More elaborately, every different version of Tetris will have its own block choice algorithm. The ones I've most commonly heard about are a "true" random generator that doesn't make any kind of judgement, a "fair" generator that generates random sequences of all seven blocks (so you /will/ get every type of block equally often, but the order in which you get the blocks within a 'batch' of six will vary)...

... And then there is Bastet, or "Bastard Tetris", which distinguishes itself by having an algorithm that chooses the worst possible block with malice aforethought.

For further reading I recommend the wiki pages here (different tetris random generators) and here (the 'official' guideline to what makes a Tetris game).

  • 2
    See also: hatetris. AFAIK no-one has ever cleared more than 30 lines.
    – user3490
    Apr 27, 2012 at 18:03

As I recall, the original version of Tetris randomly generated a permutation of the 7 blocks, and then sent those.

So, the first set of 7 blocks forms a full set... and the second set of 7 blocks forms a full set.

Meaning, for example, you only rarely had an opportunity to get a double.

I'd be curious to know what random generator was used. Given the time that Tetris was first released, it's likely that the randomness was quite deterministic.

  • 3
    This is certainly not the case in the version on the Gameboy. Apr 9, 2012 at 13:20
  • 1
    really? hm! I obviously recall incorrectly, with thanks and apologies. Nonetheless, the Gameboy version is not the original version ;)
    – Ronald
    Apr 9, 2012 at 13:26
  • discussion-here: the suggestion is that older versions actually used a larger bag (perhaps of 28 blocks?)
    – Ronald
    Apr 9, 2012 at 13:34
  • If this were true, you could never have 3 of the same block in a row. I am fairly certain I have, though. Apr 9, 2012 at 20:56

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