Here is a smartphone fan made to keep your device cooler during prolonged gaming sessions. The Memo Smartphone Radiator attaches to your iPhone or Android device and can be powered using an external battery. It comes with a clamp that adapts to phones 2.85 to 3.9″ in size.
This fan has an ergonomic design, so it won’t interfere with your gaming. It delivers rapid cooling (10-30C). You can find out more here.