On level 21 if you pay attention the four quadrants stay in the center for varying amounts of time after being clicked. Click them in order from the one which stays still for the longest amount of time to the one that stays still shortest amount of time.
I love these games. AlthoughI do have to mention that there are a lot of jumps that should be easy but end up being frustrating because the robot keeps hitting its head on the ceiling
 "Clickplay 2"){kind=icon}
 "Robot Wants Fishy"){kind=icon}
 "e7"){kind=icon}
 "Sushi Cat The Honeymoon"){kind=icon}
 "Loved"){kind=icon}