There actually is a mobile version for android (not sure about iphones) It's pretty horrible too. It was modified to be one of those free to play games with micro transactions. The gameplay is nowhere near as smooth and it literally becomes impossible to go past certain times in survival mode unless you pay up for upgrades or grind for hours on end. Even then if I remember correctly once you die a certain amount of times it keeps you from playing it after so many hours, unless of course you pay up.