There are world-class games on iOS, but the critical problem - I think - is that (i) the interface isn't subtle enough to handle fine movements (unlike the mous

There are world-class games on iOS, but the critical problem - I think - is that (i) the interface isn't subtle enough to handle fine movements (unlike the mouse or analog stick), (ii) the devices are cumbersome and tiring to use for extended periods of time, and (iii) critically, there is no tactical feedback for buttons which means that a portion of your brain is always dedicated to making sure that your thumb is 'over the A button', removing you subtly but importantly from the gaming immersion. EDIT: I also want to say that to any lurking iOS game devs - the most critical thing that seems to separate viral games from standard ones is the leveraging of a single (or a handful) or basic multitouch gestures. Angry Birds: drag and release Flappy Bird: tap Homescapes: swipe Super Mario Run: tap et cetra... Artificial buttons and joysticks are a bad idea - they do not translate well to a touch-based platform.