Digital Devil Story: Megami Tensei refers to two distinct role-playing video games based on a trilogy of science fantasy novels by Japanese author Aya Nishitani. One version was developed by Atlus and published by Namco in 1987 for the Famicom—Atlus would go on to create further games in the Megami Tensei franchise. A separate version for personal computers was co-developed by Atlus and Telenet Japan and published by Telenet Japan during the same year. An enhanced port for the Super Famicom by Opera House was released in 1995. The story sees Japanese high school students Akemi Nakajima and Yumiko Shirasagi combat the forces of Lucifer, unleashed by a demon summoning program created by Nakajima. The gameplay features first-person dungeon crawling and turn-based battles or negotiation with demons in the Famicom version, and a journey through a hostile labyrinth as Nakajima featuring real-time combat in the Telenet version. Development on both versions of the video game began as part of a multimedia expansion of Nishitani's book series. Nishitani was deeply involved with the design and scenario. The gameplay mechanics in Atlus' role-playing version of the game were based on the Wizardry series, but with an added demon negotiation system considered revolutionary for the time. Atlus and Telenet Japan worked on their projects simultaneously, playing against genre expectations for their respective platforms. The Famicom version proved the more popular with both critics and players, leading to the development of the 1990 Famicom sequel Digital Devil Story: Megami Tensei II.