The rules are very simple: you have to hit as many moles as you can.
The game has 3 modes: 1) Arcade – you have to hit as many moles as possible. If you fail to hit 20 moles the game will be over. 2) Time – you have 60 seconds to strike as many animals as you can. 3) 100 moles quest – only 100 moles will come out of the hole, you have to do your best and hit as many of them as possible.