Video game clone grouped as "Myst clones". Some video game genres are founded by archetypal games of which all subsequent similar games are considered derivatives; notably, early first-person shooters were often called ""Doom" clones", while the success of the open-world formula in "Grand Theft Auto" led to the genre of GTA clones. The genre of endless runners is based on the success and simplicity of the game "Canabalt". In these cases, games that are "clones" of another are generally not implied to have committed any intellectual property infractions, and otherwise considered legally acceptable practices, although calling such games clones is generally considered derogatory.
X (video game series) X (video game series) X is a science fiction space trading and combat simulator series created by German developer Egosoft. The series is set in the X-Universe where several races populate a number of worlds connected by jumpgates. The games feature free roaming gameplay with trading, combat, empire building, and missions; leading to the series' phrase: ""Trade, Fight, Build, Think"". The series, which was launched in 1999 on the Windows platform, consists of five base games: "", "", "", "X Rebirth", and "". "X Rebirth" introduced a new rendering engine as well as a new plot, one which "X4: Foundations"