I guess you have no idea how that stuff actually works PThere are a lot of functions and methodes in every engine that work totally different in other engines andor dont exist at all . The way you write code can be totally different too . It is simply not possible to make an engine that could support many other engines and even if you made one it would be slow as hell because it had to include a lot of stuff that are not even needed . And to be fair we dont even need such an engine . Why should a game like Hearthstone use something like the Cryengine . It doesnt need almost all of the features and it would be just way harder to write and you couldnt port it to smartphones <| sep |> Might have a fighting chance vs . a coyote .