There are weird, discoloured beings living among these nice googly-eyed creatures. If you can't spot them in time they're going to infect everyone! Very easy to play, just spot the odd one, tap him and *puff* he's going to disappear. Be careful, if you miss, you will instantly create a new discoloured creature!
Collect the points and unlock new themes to select as favourites. Favourite themes will show up more often so you'll have a better chance to increase your high score.