NEC was behind its competitors in terms of hardware (with only 16 colors and no sound support) and needed a way to regain control of the market. The first commercial erotic computer game, Night Life, was released by Koei in 1982.
Early eroge usually had simple stories, some even involving anal, which often led to widespread condemnation from the Japanese media.
There is no set definition for the gameplay of eroge, except that they all include explicit sexual content.
This most often occurs as hentai scenes of the player character having a sexual encounter with other characters.
Soon, new genres were invented: ASCII's Chaos Angels, a role-playing-based eroge, inspired Dragon Knight by Elf and Rance by Alice Soft.