Darts online - 501 game

The object of Darts game is to count down from the starting number of 501 to exactly zero.
When a player throws rounds of three darts, the sum of those darts gets subtracted from the starting number.
The dart throw is made by a single mouse pressing and releasing.
To throw the 'shaking' dart, first stop it in the desired location by pressing the left mouse button.
To increase the power of the throw, hold down the left mouse button longer before releasing it. Power indicator will show the power of the throw.
Each dart is scored by the number of the sector it lands on the target. The thin outer ring doubles these points, the inner ring triples them.
Hitting the center ( the smallest black circle) gives 50 points, while hitting the small red circular area around the center gives 25 points.
This implementation of Darts game is a single-player game, players compete for the highest score in the currently open tournament, the winner of the tournament wins the cash prize.

Game implementation features: offscreen image buffering for the whole game screen, a separate thread for the moving and the flying dart, special score count, double-checking the score on client and on server.