Atari Corp and Atari Games were separate companies by the time the NES was released. Atari Corp was responsible for the consoles and computers, while Atari Gam

Atari Corp and Atari Games were separate companies by the time the NES was released. Atari Corp was responsible for the consoles and computers, while Atari Games did the arcade games. Atari Games used the name "Tengen" for all home releases. Atari Games did both licensed and unlicensed works for the NES. Notably, Tengen Tetris was originally a fully licensed VS arcade game called "VS Tetris" before its unlicensed home release. Tengen didn't have the rights to home versions of Tetris, only arcade versions, and Nintendo did not have the rights to arcade versions. Hence Tengen/Atari Games developing an arcade version of Tetris for Nintendo hardware.