A gaming crossover occurs when otherwise separated fictional characters, stories, settings, universes, or media in a video game meet and interact with each other. These may exist as a gimmick if two separate games in question are developed by the same company. Otherwise, they may exist as a gag from a rival company. The following is a list of games in which crossovers appear in either the form of a cameo of any kind, a guest character, or the theme of "crossover" in general in a video game itself: