Tengen was a video game publisher and developer that was created by arcade game manufacturer Atari Games. Atari had been split into two distinct companies. Atari Corporation was responsible for computer and console games and hardware and owned the rights to the Atari brand for these domains. Atari Games was formed from Atari's arcade division, and were able to use the Atari name on arcade releases but not on console or computer games. When Atari Games wanted to enter the console-game market, it needed to create a new label that did not use the Atari name. The new subsidiary was dubbed Tengen, which in the Chinese game Go refers to the central point of the board (the word "Atari" comes from the same game). Tengen then made an agreement with Namco to bring some of their Famicom games to the Nintendo Entertainment System in North America before Namco opened its own North American branch in 1993. Tengen also released games by Sunsoft (another developer without a North American branch).
Tengen unsuccessfully tried to negotiate with Nintendo for a less restrictive license (Nintendo restricted their licensees to releasing only five games per year, and required their games to be NES-exclusive for two years). Nintendo refused, so in December 1987 Tengen agreed to the standard licensing terms. In 1988, Tengen released its first and only three cartridges licensed through Nintendo—RBI Baseball, Pac-Man and Gauntlet. Meanwhile, Tengen secretly worked to bypass Nintendo's lock-out chip called 10NES that gave it control over which games were published for the NES. While numerous manufacturers managed to override this chip by zapping it with a voltage spike, Tengen engineers feared this could potentially damage NES consoles and expose them to unnecessary liability. The other problem was that Nintendo made frequent modifications to the NES to prevent this technique from working. Instead the company chose to reverse engineer the chip and decipher the code required to unlock it. However, the engineers were unable to do so, and the launch date for its first batch of games was rapidly approaching.
With time running short, Tengen turned to the United States Copyright Office. Its lawyers contacted the government office to request a copy of the Nintendo lock-out program, claiming that the company needed it for potential litigation against Nintendo. Once obtained, it used the program to create its own chip that would unlock the NES. When Tengen launched the unlicensed versions of its games, Nintendo immediately sued Tengen for copyright and patent infringement. In the initial phases of trial, the court sided with Nintendo, but the sides settled before the matter was fully resolved.
Tengen faced another court challenge with Nintendo in 1989 in copyright controversy over Tetris. Tengen lost this suit as well and was forced to recall what was estimated to be hundreds of thousands of unsold cartridges (having sold only about 50,000).
Despite its problems with Nintendo, Tengen went on to produce games for the Sega Mega Drive/Genesis, Sega Master System, Sega Game Gear, Sega CD, Atari Lynx, and NEC Turbo Grafx-16. The company also published games for home computers such as the Amiga and the Atari ST. It was best-known for its ports of popular Atari arcade games, including Klax, Hard Drivin', STUN Runner, and Paperboy, although they published many other titles as well. In 1993, after Time Warner bought a controlling stake in Atari Games, the Tengen name was discontinued and home games were now released under the Time Warner Interactive (TWI) brand.
Tengen manufactured both licensed and unlicensed versions of three of their NES games. Their cartridges for unlicensed games do not come in the universally recognizable semi-square grey shape licensed Nintendo games come in; instead, they are rounded and matte-black, and resemble the original Atari cartridges.
- 720° (had a licensed version by Mindscape)
- After Burner (released as a licensed game by Sunsoft in Japan)
- Alien Syndrome (released as a licensed game by Sunsoft in Japan)
- Fantasy Zone (not related to the version released by Sunsoft in Japan)
- Gauntlet (was both licensed and unlicensed)
- Gauntlet II (had a licensed version by Mindscape)
- Indiana Jones and the Temple of Doom (had a licensed version by Mindscape and an unlicensed version)
- Ms. Pac-Man (an original port unrelated to Namco's 1985 Famicom version, which was released in North America in 1993)
- Pac-Man (both licensed and unlicensed versions in North America. It had been previously been released in Japan in 1985. Namco later released it in North America itself in 1993)
- Pac-Mania (developed by Namco, but not released in Japan)
- RBI Baseball (released as Pro Yakyū Family Stadium in Japan by Namco; was released in both licensed and unlicensed versions, in North America)
- RBI Baseball 2 (the sequels are original games unrelated to "Family Stadium")
- RBI Baseball 3
- Road Runner
- Rolling Thunder (released as a licensed game by Namco in Japan)
- Skull & Crossbones
- Super Sprint
- Tetяis: The Soviet Mind Game