do you mean so that you could have a game thats out and when you want you can issue a qr code on your website or a business card or something like that and then in game someone can just scan the code and open something new, then that would be quite hard as i dont think game maker lets you have access to the camera, plus you would have to write your own code reader to beak it up into something you can use like a dot patern or something, so it wont be easy but is something that can be done with an ext of coarse for the camera and a load of pre set paterns for what ever qr codes you will be going to use ever or drop more in an update later on, but as for game maker having it built in your out of luck.