Since its inception in 1996, The Tetris Company has pursued unlicensed Tetris clones with several games becoming unavailable as a result.

For games that replicate Tetris-like gameplay but aren't part of the Tetris series, see falling blocks genre.

Implied: visual matching

It is widely assumed in North America that 'TETЯIS', used for the title of some versions, with the backwards 'R' (Cyrillic letter 'Ya') is the Russian spelling. But this was simply faux Cyrillic typography. The correct Cyrillic is ТЕТРИС (ТЕТРИІС). Some packaging is shown ТЕТРИ☭, with the Cyrillic (Ukrainian) 'І' crossing a backwards 'С' to form a backwards ☭ (Unicode U+262D). Otherwise known as the hammer and sickle (Сърп и чук), A symbol of communism made famous on the Soviet flag.