iCade and Mfi is very different. iCade was a keyboard hack, while mfi using a api FrameWork and can do more glbasic commands actuelly can support.
So for support for mfi game controller, GameInput API is required (not hard to use, so check it out). Im do not plans to support it using official JOY commands, due limited support. MOUSESTATE is howover supported. GameInput do also support iCade, but only for iOS, not tvOS.
PS. im do still have some issues left for Greedy Mouse to it get approvede on Apple TV (Karma Miwa is ready to sale on Apple TV). This is currectly my main focus, so im can get the game out of my door (Karma Miwa is on sale). Then im will code the accelerator part on the remote controller, which is still missing.
PPS. Im have also installed the official version of tvOS now, so im can also uses AppStore now. So no more NDA and do a review of it if im wanted to do that.