This is a very simple "rhythm" game that uses the keyboard LEDs as only display method.
One of the three keyboard LEDs light up to indicate an incoming "note" and the user must press the key directly below
it to "hit the note". For example, the CAPSLOCK key lights up and the user
* on the numpad.
It works on Linux only (tested on Ubuntu) and your LEDs may or may not go back to normal. In case they don't, just press the key that turns them on and off again.