LoboBlanco: Well, I don´t have any idea what a "metagame" is :P
snowkatt: self referential and usually fourth wall breaking
ie being aware its a video game or commenting on video game tropes
saints row 4's mission from asha with love is both a parody and fourth wall breaking
deadpools game is incredibley meta
Not only self-referential, but also games about games - collecting the cards in Steam, for example, is a metagame.
Or it can be a gamification of games - achievements in games are metagames