Googling "optimus" + "fullscreen" would have helped Bungie developers a lot... As far as can remember, there has always been problems with this gpu-switching technology, among which fullscreen issue is the most common. (If I'm not mistaken, ALL of nvidia's external gpu frames are transmitted to the internal iGPU, that is the only chip actually connected to the laptop display - 4600 igp in my case) Performance also seems inconsistent at the moment with this GPU range. The included youtube video shows great framerate. I have the same gpu & better cpu but get nowhere near this guy's performance (25fps approx, i'd say). Bring us true exclusive fullscreen mode please. Last word of advice: for the Lenovo Y50 (my laptop), the required 4K upscaling is another headache for developers (I'm thinking of the emulator RPCS3 that runs great in a window, and is painfully slow in fullscreen). Food for thought.