The PC Engine CD-ROM² add-on was released in Japan for the PC Engine console in April of 1988. The North American version, known as the TurboGrafx-CD, went on sale in 1989 for the TurboGrafx-16 (the North American version of the PC Engine).
While it had little success in North America, the device boosted sales for the PC Engine in Japan. It helped the PC Engine outsell the NES for a while (up until the release of the SNES) and become the second best-selling console of the 16-bit era, behind the Super Famicom (which later planned its own PlayStation CD add-on) and ahead of the Sega Mega Drive (which later had its own CD-ROM add-on, the Sega CD).
This device was the first system to introduce the CD-ROM format (which was officially released by Sony and Philips just months before its release), predating the FM Towns computer by a couple of months and the Sega CD console add-on by several years. The platform would see a full redesign in 1991 (October 1992 in North America) as the PC Engine Duo, or TurboDuo. The Duo console merged the card-playing base console an CD-ROM add-on into one piece of hardware.
Initially, playing CD-ROM games on a TG16 required the use of a System Card, which carried the BIOS data required to properly access the TGCD hardware. When the Duo was released, an updated version of this firmware was included in the console itself, booting whenever the system was powered-up without a card inserted into the card slot. The firmware released with the Duo was upgraded to allow the platform to play "Super CD" releases. Owners of the existing, non-Duo version of the platform were forced to purchase a new system card (the "Super System Card") to play these new discs. In Japan, one further upgrade, known as the Arcade Card, was released. Only a handful of games (known as "Arcade CDs") were released that require the Arcade Card upgrade. The Arcade Card was not released outside of Japan.
Discs released for the TGCD hardware are region-free and can be booted on any version of the PC Engine hardware, assuming that the appropriate system card is present. Both the Duo models and the TGCD add-on have built-in memory, allowing players to save progress and scores in supported titles. By pressing Select at the system's boot screen, a data management screen can be accessed.
An online modem was also planned for the console in Japan, in order to compete with the online services of the Nintendo Famicom and Sega Mega Drive (and later the Super Famicom), but it was eventually cancelled.
As the first system to use the CD-ROM format, it introduced several new features to home video games, including a very large amount of storage space (540 MB of data, in contrast to the 1 or 2 MB cartridges of that era), cinematic cutscenes and voice acting (both previously limited to laserdisc arcade games, i.e. interactive movies), and CD-quality Red Book audio (a huge improvement over the chiptune audio of previous home systems). Some of the first home video games to demonstrate these features include No-Ri-Ko (1988), Far East of Eden: Ziria (1989), and Ys I & II (1989).
Full-motion animation was not used as frequently in early games for the TGCD, this being before the "multimedia gaming" era that the Sega CD and the 3DO fell into. The cinematics in the games were usually more anime-like in nature (and rendered in-engine), which served to partially hide the limitations of the unit's single-speed CD drive, with some of the most beautiful cutscenes being present in games like Ys Book I & II, Ys III and IV, Far East of Eden, Cosmic Fantasy 2, and a remake of Valis: The Fantasm Soldier. The system was more widely supported in its native country of Japan, which received a much larger library of games for the device than North America did.
Today, the system is primarily known in North America as a home for quality shoot-'em-ups, like Lords of Thunder, Gate of Thunder, R-Type Complete CD, and more, as well as for RPG's with cinematic cutscenes and CD-quality audio soundtracks (such as the early Ys games, for example).