Night Life (1982) was the first commercially released eroge.
GunBlaze, Eve Burst Error, and others) were re-released (usually on a console system) with all explicit content removed. The matter is further complicated by the fact that some hentai games (e.g. Bishōjo (美少女, 'pretty girl' also referred to as Gal Game) is a rather vague designation, often used to describe any game in which the player character interacts with attractive anime-style girls, regardless of the adult content. In Japan, the preferred term is Eroge (エロゲ, short for 'erotic game'). Hentai (Japanese 変態, 'perverse' can also be understood as 'shape-changing' or 'weirdly shaped') is the term commonly used in the West for such games.
This group may include any game with significant amounts of nudity and/or explicit sex scenes that was either made in Japan or clearly imitates the Japanese way of making such games.