If you're experienced at programming, you may be able to run a very slow version of steamOS. As for the xbox controller, bluetooth connection between many devices (xbox controllers, wii remotes, ps3 controllers, etc) were blocked in an android 4.4.3 patch. I have tried to do something similar with my note 3, and those were some problems I had faced. If you're looking for a portable controller-based PC gaming experince, I recommend the nvidia shield portable. If you don't want to pay the extra money for for that, you can always get a rooted ROM and overclock the device (at your own risk). Also, I think there's a way to get windows 95 on an android device.