Finally it is playable

Indispensable for games or dexterity is required commands
Easy to use and installation of the software and the Bluetooth connection to enable to think of course.
No charge cable attached but it is the same classical micro USB cable as my Samsung S4
Compatible of several games
For example SuperNintendo emulator it is possible to remove the buttons of screens that are no longer useful so.
There are versions with more button but most of Smartphone games merely those of this interface.

For use with the phone slipped upper or not
Has its own battery

Marc