In 1982, Beam Software and publisher Melbourne House brought Tolkien’s world to computers with a text adventure based on The Hobbit. (An emulator of the ZX Spectrum version is available to play online.)
Back then, the original licensor — in this case the Tolkien Estate itself, or Tolkien Enterprises (now Middle-earth Enterprises) — would allow licensees to sometimes resell the license. It appears that at this time the animated films shared a license with the first round of video games.
Enthusiasm for Tolkien adaptations ramped up in the wake of the 1980 animated film The Return of the King, based on the final book in Tolkien’s trilogy. Following Beam’s text adventure, developer Interplay Productions turned over an in-production fantasy role-playing game, changing the theme to a Lord of the Rings adaptation. Writer Jennell Jaquays, now the owner of Dragongirl Studios, said she was hired by Interplay to write background and some “adventuring” for the RPG.
All of this is according to author Alexa Ray Corriea for Polygon.com. You can read the entire article right here.
The story Tolkien’s own letters regarding adaptation and is a nice overview with some details of Tolkien’s works in other places including movies that many fans don’t know is far from the final word of adaptation. It is long but recommended reading. The author does some real journalistic work here, contacting sources, getting quotes and really getting down a history that will help others get a great overview with a lot of salient details as well.