I am going to show you a game. It costs about a buck on the Play Store and is very fun. However, once you begin playing it, you will have roughly five minutes until you either scream, demand a refund, or your head explodes. There are no other options. The game is called Puk. And it is insane.
The concept is simple. At the start of each level, you are given a set number of slingshot-able pucks (I get it!). You have to hit a number of large white circles on the play field with said pucks (...ohhh.