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One randomizer I left out of this article (for the sake of brevity) is the Game Boy's version. It has much more bias as detailed in the post below. According to

One randomizer I left out of this article (for the sake of brevity) is the Game Boy's version. It has much more bias as detailed in the post below. According to The Tetris Company founder it was also a last minute addition to the game. When they were testing a late build by Nintendo, it had a fixed sequence or something like that. So Nintendo flew in some devs to where Henk was, and over the weekend they programmed this new randomizer. https://tetrisconcept.net/threads/randomizer-theory.512/page-9#post-51035 https://tetrisconcept.net/threads/randomizer-theory.512/page...

ginko 7y ago
It seems weird that they leave out the GB version of all things since it's probably the most popular version of Tetris by far.
Sniffnoy 7y ago
Oh yikes it's not left/right symmetric! Do you have a direct description of the algorithm? Extracting it from those forum posts seems a bit difficult.
- pixelbath 7y ago
  http://harddrop.com/wiki/Tetris_(Game_Boy)#Randomizer http://harddrop.com/wiki/Tetris_(Game_Boy)#Randomizer
  - Sniffnoy 7y ago
    Thanks! To repeat it here: we assign each piece a piece a vector of 3 bits; thinking of these vectors as numbers from 0 to 7 (or rather 0 to 6, since 111 is unused), the pieces go in the order (L, J, I, O, Z, S, T). Note that this assignment is not left-right symmetric; there's no particular relation between a piece and its mirror image. Like, L is 000, but J is 001; and Z is 100, but S is 101. That seems like kind of a dumb mistake -- it would've been easy enough to maintain symmetry. (As just one example among the 24 possible ways (assuming 111 must be kept unused), one could have used instead (O,J,I,Z,L,T,S).) Anyway, each turn you pick one of these at random, and you look at the last two pieces; let's call these previous_1 and previous_2. If -- considering pieces as their sets of 1-bits -- we have both that previous_1 is a subset of previous_2, and that the picked piece is a subset of previous_2 -- we reroll. After the third try we just take the piece no matter what. Note that this means that there are some weird interactions between the previous two pieces. Like, if previous_1 is not a subset of previous_2, then we won't reroll no matter what piece we picked, so the new piece will be totally random. But if it is, then we may or may not reroll. Definitely pretty weird. Have to wonder how on earth this was thought up...

ginko 7y ago

It seems weird that they leave out the GB version of all things since it's probably the most popular version of Tetris by far.

Sniffnoy 7y ago

Oh yikes it's not left/right symmetric! Do you have a direct description of the algorithm? Extracting it from those forum posts seems a bit difficult.

pixelbath 7y ago
http://harddrop.com/wiki/Tetris_(Game_Boy)#Randomizer http://harddrop.com/wiki/Tetris_(Game_Boy)#Randomizer
- Sniffnoy 7y ago
  Thanks! To repeat it here: we assign each piece a piece a vector of 3 bits; thinking of these vectors as numbers from 0 to 7 (or rather 0 to 6, since 111 is unused), the pieces go in the order (L, J, I, O, Z, S, T). Note that this assignment is not left-right symmetric; there's no particular relation between a piece and its mirror image. Like, L is 000, but J is 001; and Z is 100, but S is 101. That seems like kind of a dumb mistake -- it would've been easy enough to maintain symmetry. (As just one example among the 24 possible ways (assuming 111 must be kept unused), one could have used instead (O,J,I,Z,L,T,S).) Anyway, each turn you pick one of these at random, and you look at the last two pieces; let's call these previous_1 and previous_2. If -- considering pieces as their sets of 1-bits -- we have both that previous_1 is a subset of previous_2, and that the picked piece is a subset of previous_2 -- we reroll. After the third try we just take the piece no matter what. Note that this means that there are some weird interactions between the previous two pieces. Like, if previous_1 is not a subset of previous_2, then we won't reroll no matter what piece we picked, so the new piece will be totally random. But if it is, then we may or may not reroll. Definitely pretty weird. Have to wonder how on earth this was thought up...