A set of rules used by a game development company for almost every game they publish. It is much cheaper to create the system once, and then tweak it for a specific game than to develop a unique system for each game. It also helps with sales because players will already know the basics, and won't have to learn a whole new set of rules. However, it can backfire if the system doesn't fit the genre they're trying to apply it to. Most House Systems end up as Universal Systems, if they didn't start out that way. Has nothing to do with an antisocial genius's idea of how to perform medical diagnoses.