HappyFunTimes lets you use smartphones as controllers. Make great party games for 10 to 100 or more players! Make installations where users can use their phone to interact. No software required on the phone. The phone uses HTML so you can design infinite types of controllers.
Make controllers that use device orientation or acceleration. Make controllers that change based on the mode of the game. Make asymmetric controls where some players have different controls than others. Use Google Cardboard as a controller.
See videos of example games here as well as video tutorials
You can even make games that span machines