How many iphones does it take to equal the processing power of a modern desktop with a beefy GPU? Well, we can try to guess. An iphone has a 5 watt charger. A decent desktop has a 500 watt power supply. So, probably about 100 iphones = 1 desktop in processing power.
Also, it would only be working on the iphone when the game is running. A desktop is instead running it all the time. So, assuming the iphone user plays 30 min a day....that's 4800 iphones = 1 desktop.
Honestly, I don't see the point of this.