Thanks for your response.
But I actually already know how to do all that.. I just want the game to auto-detect if I'm on desktop, and adjust the game's width and height to a fixed size. Simply to make sure it doesn't fill up the whole screen.
So when the game is accessed on PC, it'll load mysite.com/Game, same URL for mobile. Thing is, like I mentioned, it'll eat up all the space on PC, while that's when I want fixed dimensions. Because on big screens it'll be all blurry!
Hence I'm asking if there's any way to have the game to detect on which platform you are, without having two versions of the game (due to different export settings) but apparently there aren't any actions available to set the game's dimensions?