The microbit controller is a tiny micro computer in the vein of Arduino and Raspberry Pi. It has been developed by the BBC to stimulate children to learn programming. See http://microbit.org. It looks like this.
Just for fun I have created a simple game. The code can be found here.
The object is to catch the falling light: you have to press the correct key just after it disappears at the bottom. For the left column you have to press A, for the right B, for the middle column A+B. If you are to early, you will see a X (and hear a low beep if you connect a buzzer to pin 0), if you press correct, you will see your score (and hear a high beep if you have a buzzer connected).
I may try to make it a bit more sophisticated, but the aim was not to make a perfect game. Rather I wanted to see whether it was feasible to make an enjoyable game within the constraints of the microbit.