The zombies want to occupy your hotel and have a big party in the penthouse. You as a porter aren't willing to let them enter and you barricade the door. You haven't reckoned with the fact that zombies are excellent balloonists, though, so they can reach the penthouse via the air. You're an inventive guy and you find a solution: you simply use a classic bow and arrow to shoot all the balloons out of the air!
Use the mouse to aim. Hold the left mouse button to bend your bow and release to loose off an arrow.