Moscow, 1984: Alexey Pajitnov writes a falling-block puzzle on an Elektronika 60 at the Dorodnitsyn Computing Centre of the USSR Academy of Sciences. The pieces are the tetrominoes — the seven ways four cells join edge to edge, up to rotation. This panel is runnable: it enumerates the tetrominoes from scratch, proves the counts 5 free / 7 one-sided / 19 fixed, and drops pieces onto a small board where a full ten-wide row clears and the rows above fall.
source Alexey Pajitnov, Tetris, 1984, written on an Elektronika 60. Complexity result: E. Demaine, S. Hohenberger & D. Liben-Nowell, Tetris is Hard, Even to Approximate, 2002. Room: THE MACHINE. Rendered, not quoted.
Alexey Pajitnov built the first Tetris at the Dorodnitsyn Computing Centre of the USSR Academy of Sciences, on an Elektronika 60 terminal — the pieces first drawn from bracket characters on a text display. It spread on floppies across Moscow institutes before it had a publisher.
Then the Cold-War licensing saga: rights ran through the UK, Japan and the USSR’s foreign-trade agency Elorg; disputed sub-licences collided until Nintendo secured the handheld rights and shipped it bundled with the Game Boy, 1989. Pajitnov saw no royalties for years — the software left the USSR faster than the state could price it.
A tetromino is four unit cells joined edge to edge. Count them three ways: free (rotations and reflections identified), one-sided (rotations only), fixed (every rotation distinct). The engine enumerates all four-cell shapes from a single seed and sorts them:
| class | count |
|---|
The classic game uses the 7 one-sided set — I O T S Z J L. S/Z and J/L are mirror pairs, so they collapse to 5 free shapes; letting every rotation count separately gives 19 fixed.
Tetris founded the falling-block genre and became one of the most-ported games ever written — onto nearly every computer, console and phone platform that has existed.
Its descendants (Columns, Puyo Puyo, Dr. Mario, the endless Tetris variants) all inherit the same core: a bounded well, gravity, and a line that vanishes when full. The mechanic outlived the machine, the company structure, and the country it was written in.
Pick one of the seven one-sided pieces, rotate it, choose a column, and drop. The board is 10 wide and seeded with a nearly-full bottom row — drop the default I at column 3 to complete and clear it.
10 × 8 well. Each piece covers exactly 4 cells (gold). A hard drop settles the piece on the floor or on what is already stacked.
Lines cleared this session: 0
LINE-CLEAR logic. After a piece settles, every row that is filled across all 10 columns is removed; each row above it drops down by one and an empty row is added at the top. Cells not in a full row are never disturbed.
| piece in the bag | cells | = 4 ? |
|---|
The witness re-counts the active piece bag on every action: it asserts there are exactly 7 pieces and each covers exactly 4 cells, and re-derives 5 / 7 / 19 from the enumerator. Inject a five-cell shape (window 8) and it turns red.
So the toy hides a real wall: there is no known efficient algorithm that plays optimally even with perfect foreknowledge. The falling pieces are a genuine combinatorial-search problem, not a reflex game with a tidy solution.
“Tetris is just a toy.” Cut. Offline Tetris is NP-complete (Demaine 2002) — the toy contains an intractable search problem.
“There are only 5 tetromino shapes.” Cut. Five is the free count; the game uses 7 one-sided pieces because it does not allow mirroring, and there are 19 if every rotation is counted.
“Soviet software could not compete.” Cut. Tetris was a Soviet export that outran its own state — it shipped worldwide on the Game Boy (1989) and outlived the USSR itself.
The red move: slip a five-cell pentomino into the piece bag. The board still draws, but a Tetris piece is a tetromino — four cells, always.
Inject the pentomino and the witness (5) re-counts the bag: it now holds 8 pieces and one covers 5 cells, so “every piece has exactly 4 cells / there are exactly 7 one-sided” turns red. The attack is real and it is caught.