The rules are simple:
Look at the color of the word in the center of the circle and tap that color. Don't be fooled by the word itself. It's the color of the word that matters.

Sounds simple? You'll be surprised at how challenging it is.

You score 10 points plus a bonus for each correct tap, but you have to be quick.
The bonus drops quickly to 0 if you wait too long. You also get additional time added for every correct tap. If you tap the wrong color a time penalty is taken.