The games may've been out in the mid-to-late-1990s, but I think the manga and a couple written stories were out in circulation well before that. I don't know if it'd be right to say the series was abandoned, though. Many shows in the States had books out for years before they finallly got movies and TV-series made about them (case-in-point, my dad said he read a series of books sometime in the 1980s chronicling the adventures of an elite military unit that traveled to alien planets using a device that could create wormholes; about ten years later, they made Stargate and, later, Stargate SG-1, which lead to the spin-off Stargate Atlantis and now there's Stargate Universe. Likewise, Jurassic Park was on bookshelves for years before it finally got turned into a motion picture, and then they made two sequels).
