Here’s a video by Dilshan Jayakody demonstrating the USB custom hardware interface for Unity3D:
The custom hardware unit used in this demo is build around Microchip’s PIC18F2550 MCU. This custom USB controller consists with 4 push buttons and linear potentiometer. In supplied demo user needs to control aircraft with those buttons and potentiometer. According to the game logic 4 buttons are used to control the flying direction and flying angle of the aircraft and potentiometer is used to control the speed of the aircraft.