From Sega Retro
Tetris is a 1988 Sega System 16 game developed and published by Sega. It was licensed from Atari Games (credited as Tengen) and Mirrorsoft, who held the rights to produce Tetris arcade games at the time. A less powerful version was also released for Sega System E hardware. Both versions are unrelated to Atari's arcade version, released in the same year under the same name.
Sega attempted to port the game to the Sega Mega Drive, however sales were blocked by Nintendo who owned the home console rights to the franchise (they had taken Atari's home console division, Tengen to court over a similar incident on the NES). As such, only about 10 cartridges were produced, all of which were only released in Japan. This version is now a rare collector's item, being sold in auctions for up to US$16000. Because Nintendo had no authority over the arcade versions, the Sega Mega Drive port was brought to Mega-Tech hardware in 1989.
The System 16 version of Tetris does not add anything to the original formula, but at the time was the best looking version of the game available. If the player gets a tetris (i.e. he/she clears four lines at once), the background will change.
The Tetris license has passed through numerous publishers, but Sega did have another attempt with 1999's Sega Tetris. Several games share the same theme tune (and monkey helper) as the System 16 version of Tetris, including the Sega Saturn game, Tetris S.
This version of Tetris was the most popular arcade version of Tetris in Japan, and many future Tetris games were based off how this one operated. For more technical details, see Sega Rotation.
System 16 Version
Mega Drive Version
System E Version