The SteelSeries Free is a bluetooth game controller for Android. It has a solid feel and fits well in the hands, with rubbery grip all around. The Bluetooth communication supports HID mode making it a great bluetooth controller working on iOS, Android and Desktops.
It features dual analog sticks, a d-pad and 4 buttons on face. The analog sticks also have a fantastic feel to them. The controller comes with a case to protect from dust. Battery life is said to be excellent.
The SteelSeries Free has a website that lists all supported games. The list can be found here: faq.steelseries.com. There are plenty of games supported, and as with most Android controllers, the list grows exponentially when you also consider emulatores.