Reaction game
Create a small target clicking game that works on reaction time to scale difficulty. When the game starts, fill a circle on the screen in a random location. The objective is to click this as quickly as possible.
When the target is clicked, move it to a new position and adjust the radius to be proportional to the time taken. If the user takes more than 1 second (1000ms) make the circle slowly grow larger.
Show the number of targets hit, and the number of milliseconds of the fastest reaction - this could look similar to the example below:
