Hi I wonder if it is possible to send a signal to an external device vai USB.
For example if my player took damage could an output send a signal to the usb device, even say if it was a usb light that flashed evreytime a player was shot.
I really want to hook up my electric shock quazzar gun to the game so when you take damage you get a shock.
You could use the C# SerialPort class to communicate with serial devices, like a FTDI USB module or an Arduino board. A simple and useful FTDI module is the DLP-IOR4: it connects to USB but appears to the system as a serial port; this module has four relays that can be controlled by sending single characters to the serial port:
Another alternative is the DLP-IO8-G module: 8 channels that can be individually used as digital outputs, analog or digital inputs.
Anyway, you would have to use the SerialPort class; take a look at this answer, where Unity communicates with an Arduino board (microcontrolled USB board) - once the COM port is open, sending single character commands is an easy task.