To be honest, really all smartphones need to be able to play games like 100x better is some kind of small physical directional input.
The reason 90% of smartphone games suck is because of on-screen d-pads/sticks, if you could use even something like a trackball or small analog nub to control a central character/vehicle it would make about 20 different major genres of games far more playable.
Maybe you could even add L/R style shoulder buttons for primary attack/jump commands too.
That would be good enough to make some decent games. You don't neccessarily need to have one of those giant button monstrosity add-ons with 10 buttons + 2 analogs + d-pad on them IMO. No one wants to carry around a phone like that and a slider design is fat and ugly looking.







