Tetris Tengen is an unlicensed version of the classic puzzle game developed by Tengen for the Nintendo Entertainment System. Released in the late 1980s, the game included a unique two-player simultaneous mode absent in Nintendo's official release. Following a legal dispute over licensing rights, Nintendo secured the official rights, leading Tengen to destroy unsold cartridges.
Tengen, an Atari label, released an unlicensed version of Tetris for the Nintendo Entertainment System. After they lost a lawsuit to Nintendo, which acquired the rights from Russia to port the game to home consoles (they already had the handheld consoles rights), Tengen had to destroy every spare cartridge unsold at the time.
The Tengen game featured a two-player simultaneous mode not available in Nintendo's version