By 1984, 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 Japanese nomenclature of the board gameGo refers to the central point of the board. Tengen then made an agreement with Namco to bring some of their games for the NES over to America before Namco opened its own American branch in 1990. Tengen also released games by Sunsoft. Tengen unsuccessfully tried to negotiate with Nintendo for a less restrictive license. Nintendo refused, so in December 1987, Tengen agreed to Nintendo's standard licensing terms. Tengen incorporated on December 21 that year. In 1988, Tengen released its first and only three self-published games licensed by Nintendo: R.B.I. 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. Tengen announced that they were going to release their own cartridges in December 1988. When Tengen launched the unlicensed versions of its games, Nintendo immediately sued Tengen for copyright and patent infringement. This began a series of lawsuits between the companies which would not be settled until 1994. Tengen faced another court challenge with Nintendo in 1989 in copyright controversy over the two companies' NES versions of Tetris. Tengen lost this suit as well, and was forced to recall what was estimated to be hundreds of thousands of unsold cartridges of its version of Tetris. Tengen went on to produce games for the Sega Genesis, Master System, Game Gear, and TurboGrafx-16, as well as publish a localized Sega CD title. The company also licensed games for home computers such as the Amiga and the Atari ST, most of which were published by British companyDomark. 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 1994, with the lawsuit against Nintendo settled and after Time Warner bought a controlling stake in Atari Games, the Tengen, Atari Games, Time Warner Interactive Group entities were all consolidated into Time Warner Interactive.
Tengen manufactured both licensed and unlicensed versions of three of their NES games. The cartridges for their unlicensed games did not come in the gray, semi-square shape that licensed NES games came in; instead, they are rounded and matte-black, and resemble the original Atari cartridges. ;Licensed and unlicensed
