I saw a video and some discussion where people just plug and play gamepads on to Android phones.
I've got a Samsung S5 mini (SM G800F, Android 4.4.2, not rooted). Bought a wire USB SNES Clone + OTG from ebay, plugged to my phone but nothing happened: tested on games, an app to debug gamepads, with a different and new USB Gamepad etc; I thought the USB OTG was damaged, because I tested with two different usb gamepads, so I bought a new setup ( http://www.ebay.co.uk/itm/301836055385 ) + a different OTG cable from a different manufacturer. It doesn't work!
Used this app to check for OTG support: https://play.google.com/store/apps/details?id=com.btssm.doihaveotg
It's supported but no devices are listed / none found;