The GG button (link to original website) is a button that yells “GG” when you press it. Similar to the Staples Easy Button.
I modified it so that it has a USB port and it becomes a USB keyboard when you plug it into a computer. When you press the button, it types out a certain key sequence. The key sequence is such that it chats “GG WP” to an opponent in Starcraft II, and then surrenders the game (by pressing F10, then ‘n’).

http://imgur.com/a/OeTzA

Download the microcontroller source code here

This entire project is very similar to my USB business card

If you want to do this modification yourself, your tasks are to:

1. build the circuit on a small piece of prototyping perfboard (or PCB if you have time)
2. program the AVR ATtiny85 microcontroller with the compiled source code .hex file (I found out you need to disconnect the 1.5K resistor before doing this), look for a general AVR programming tutorial on how to do this
3. mount a USB mini-B connector onto a piece of PCB with the footprint, and solder some wires to it
4. open up the GG button
5. cut a hole for the USB port, I used a rotory tool to do this
6. glue your USB connector in place, I used hot glue
7. solder some wires from your circuit to the existing circuit, see schematic for the connections
8. glue your circuit in place
9. reassemble the GG button