Hmm, I tried running the apk on an android handheld (Retroid Pocket 4+) and things more or less worked excellently, until I had to shoot. There doesn't seem to be a bound key for that? Since it's supposed to be R2 on the OUYA, maybe it's having trouble recognizing modern trigger buttons?
I didn't expect it to work at all, to be fair, since it isn't an intended platform. But, hmm. Any tips on how I might tweak this? Or perhaps some plans for remappable buttons?