People always complain about on screen controls on iPhone games. Well a lot of people have old iPhones and iOS devices laying around, if not multiple devices. Why not put them to use and allow Bluetooth connectivity for it to be used as a track pad. You can prop your phone up on the desk and just use a old iPhone 4 or something as a impromptu gaming controller. Like a Bluetooth controller option. You can even use HDMI out without needing to hold something attached to a cable.