Eroge

An eroge (エロゲ or エロゲー, erogē^?, pronounced [eɽoɡe]; a portmanteau of erotic game: (エロチックゲーム, erochikku gēmu^?)) is a Japanese pornographic video game.

Japanese eroge, also known as H-Light novels or hentai games, have their origins in the early 1980s, when Japanese companies introduced their own brands of microcomputer to compete with those of the United States. Competing systems included the Sharp X1, Fujitsu FM-7, MSX, and NEC PC-8801. 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. Thus came the erotic game. The first commercial erotic computer game, Night Life, was released by Koei in 1982. It was an early graphic adventure, with sexually explicit images. That same year, Koei released another erotic title, Danchi Tsuma no Yuwaku (Seduction of the Condominium Wife), which was an early role-playing adventure game with colour graphics, owing to the eight-color palette of the NEC PC-8001 computer. It became a hit, helping Koei become a major software company.

...
Wikipedia