Named after the "Origin of Heaven", i.e. the center point on a go board (similar to how the "Atari" name was also a go reference), Tengen was founded in 1987 & initially started off as your standard third-party Nintendo licensee, releasing Gauntlet, R.B.I. Baseball (a localization of the first Famista game), & Pac-Man for the NES as official releases in mid-to-late 1988. The latter two games were the result of Atari Games' close relationship with Namco, which had been majority owner of Atari Games from 1985 to 1987. At the time Namco had infamously decided to not agree to be a licensee for Nintendo of America, due to the terms, instead preferring to license its Famicom games out to other companies for international release, like Bandai, Sunsoft, & Tengen; Namco wouldn't publish its first NES game until 1993. Similarly, Tengen was also no fan of Nintendo's licensee terms & never planned on staying official, so after those initial three games it went rogue & became an unlicensed third-party, illegally acquiring a copy of Nintendo's lock-out program, so as to bypass it, by telling the US Copyright Office that they needed it for potential litigation against Nintendo. The initial unofficial releases would start a legal battle between Nintendo & Tengen that would hound the latter for pretty much its entire life (under that name, at least), during which Tengen would eventually find fairer pastures over with Sega of America & its Genesis, Game Gear, & (in Europe) Master System, among some other short-lived deals on other hardware, like TurboGrafx-16, PCs, & even the SNES (via officially licensed third-parties, like Mindscape & THQ, for that last one).
However, Tengen (& Atari Games) wasn't solely operating in North America & Europe. Established in 1988, Tengen, Ltd. was Tengen (Inc.)'s Japanese subsidiary that not only released Japanese versions of Tengen's titles, plus both James Bond 007: The Duel & MIG-29 Fighter Pilot for Domark, but also did some development of its own; from here on out I'll just refer to it as "Tengen Japan". More often than not this was in regards to port jobs, but occasionally Tengen Japan developed original games, though the only one of those that ever saw release outside of Japan would be 1991's Magical Puzzle Popils for the Game Gear. And, in that case, we reach the subject of this overview: Japan-exclusive releases! Shockingly enough, there were only seven games (via eight releases) put out by Tengen, & its later incarnation of Time Warner Interactive, that only ever saw release in Japan (at least back in the day, for two of them), and they actually wind up coinciding with the final years of Atari Games' console division, in general. So let's go over Tengen & Time Warner Interactive's Japan-exclusive games, all while seeing how an infamous third-party console developer/publisher eventually got put out to pasture.