A doujin game (同人ゲーム) is a game made by native Japanese, often sold in physical print at booths through Comic Market every August and December.
Doujin circles range from single creators to groups, to collaborations with doujin artists, doujin musicians, and other doujin game makers/circles. Doujin games range widely in variety, in everything from every genre. They may or may not include elements from prior official games; typically elements displayed in doujin games are reflections of a doujin circle's inspiration. Rather than fan games of official characters or settings or stories, some doujin games are lead in a completely original style such as Houkai Mura, a doujin game made along the lines of Ghouls'n Ghosts (Daimakaimura).