1. The four-celled blocks in Tetris are called "tetrominoes."
2. Tetrominos are the four-celled variant of the polyomino, which is a geometric term that predates Tetris. Polyominos have been featured in various games since 1907.
3. The creator of Tetris initially wanted to make a game using five-celled polyominos, called tetrispentominos, but it was too complicated since there are twelve different shape variations for pentominos, and only seven variants for tetrominos.
4. Each of the seven variants has a name: O-Tetromino, I-Tetromino, T-Tetromino, L-Tetromino, J-Tetromino, S-Tetromino, and Z-Tetromino.
5. Tetris got its name from the portmanteau of the Greek word "tetra" meaning "four" (because of the four-celled tetrominos) and "tennis" (which was the creator's favorite sport.)
6. The 10x20 cell grid Tetris is played on is called the "well" or "matrix"
7. Although Tetris debuted in 1984, its creator, Alexey Pajitnov, didn't see any money from the game until the mid-90s, when the rights to the game were released by the Soviet government.
8. While his software company, AnimaTek, suffered financial difficulties, Vladimir Pokhilko, who is often credited as the co-inventor of Tetris, killed his wife and son before killing himself.
9. According to Guinness World Records, Tetris is the most ported game in history, appearing on 65 different platforms.
10. Tetris was also the first video game to be played in space. A Gameboy version of the game spent 196 days orbiting the Earth aboard the Mir space station.
11. The original purpose of Tetris, according to its designer, was to help make computers seem less intimidating to casual users.
12. There exists an algorithm that, in theory, will let you play one game of Tetris forever.
13. However, researchers at the University of Erlangen-Nuremberg proved that it's impossible to create a strategy for a never-ending Tetris game.
14. The famous Tetris song is an arrangement of a Russian folk tune called Korobeiniki, which tells the tale of a girl who haggles with a peddler over the price of his goods (sexual metaphor intended). It even has lyrics.
17. When a person spends a lot of time doing a pattern-based activity, they start unconsciously thinking and dreaming about the activity. This phenomenon has been dubbed the "Tetris Effect."
18. Playing Tetris can actually increase the thickness of the cortex by up to half a millimeter. The cortex is the part of the brain responsible for memory, attention, perceptual awareness, thought, language and consciousness.
19. Playing Tetris after a traumatic event may reduce the occurrence of negative flashbacks and post-traumatic stress disorder (PTSD).
20. A Plymouth University study found that playing Tetris can help you lose weight, cut back on drinking, or quit smoking.
21. Playing Tetris could also help fix a lazy eye.
22. The smallest game of Tetris ever played required an electron microscope and 42 glass microspheres.
23. It's also possible to play Tetris on old HP 546000B Oscilloscopes.
25. The feature that allows you to slide a piece into place just as it hits the bottom is called a "soft drop" and wasn't developed until five years after the game's release.
26. The original PC version of Tetris came with a "Boss Button", so people playing at work could press a key and switch to a spreadsheet when the boss walked by.
27. Pajitnov's first Tetris sequel, in 1989, was called Welltris, and it added a third dimension to the game. It was not very popular.
30. Tetris 64, released in Japan only for N64 in 1998, added a diabolical feature that measured the player's heart rate and sped up the game as the heart rate increased.
31. There are many variants of Tetris, but the one created for the Nintendo Entertainment System is considered the canonical classic and is used in the annual Tetris World Championships.
32. Sega halted Mega Drive (the Japanese name for Sega Genesis) versions of Tetris after a legal battle with Nintendo - as a result, the few existing copies of the game are worth up to $16,000, and a copy signed by Tetris' creator was put up on eBay for $1 million.
33. There is a worrying and stress-inducing "Tetris" edition of Jenga.
34. Tetris fan fiction can be found on fanfiction.net. Some of it is deeply profound.