Franchise: tetris

Named after the Tetris game series, The Tetris Effect (or Tetris Syndrome) occurs when a person's thoughs, mental images and dreams are impacted by the prolonged devotion to an activity. One such example being playing Tetris for a long time, then subconciously thinking about how shapes in the real world could fit together or seeing the "tetrominos" at the edge of one's field of vision when falling asleep.

There was an official two-player board game version of Tetris made by Tomy.

Researchers at McGill University in Montreal discovered that Tetris could be used to help correct amblyopia, commonly known as a "lazy eye." Using head-mounted video goggles, the treatment made the lazy eye focus on the falling shapes, which the researchers made high contrast, and to have the dominant eye focus only on the background grid, which was rendered in low contrast. Patients using this method showed four times the improvement rate in their vision, as opposed to those using the traditional eye-patch treatment.

A study by the Plymouth University in the U.K. has shown that playing Tetris can lower a person's food cravings by 25 percent.

Because the game was made using Soviet Union resources, none of the developers received any royalties when the game was first released.

Tetris got its name by creator Alexey Pajitnov combining the words 'tetra' and 'tennis'. Tetra is a Greek numerical prefix meaning 'four', and tennis was Alexey's favorite sport.

SEGA had released their own version of Tetris exclusively in Japan for the Mega Drive console (known as the Genesis in the U.S.) in 1989 which is considered to be the rarest version available. After Tengen's legal battle with Nintendo, Sega subsequently pulled the game from shelves with only approximately 10 copies known to have been bought. In 2011, one copy of the game was sold on eBay for $1,000,000, signed by the series creator Alexey Pajitnov himself.