Gamepad Joystick MAXJoypad - Play PC games using your smartphone or tablet as gamepad, joystick or racing wheel.
Remote Mouse - Turn your smartphone into a wireless touchpad and keyboard now!
Monect - Make the best use of sensors on smart device to control PC, simulate steering wheel, game-pad...
LEA Extended Input - iOS/Android app with windows server to control functions in games via your smartphone/tablet.
KDE Connect - Integrate Android with the KDE Desktop
Wifipad - WifiPad transforms your iPhone/iPod Touch into a wireless gamepad.