It is based on the famous game of darts.
You need to throw darts and hit the annoying flies. Flies fly away and return, but when they creep over the wall you can kill them.
You earn one point for each killed fly.
Peculiar feature of the game is that a player can easily change the background image to any one he/she likes, including that used for advertising.
You need only a mouse to play. Time is unlimited.