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.