This is one of the best games you can play in your browser. If you havent tried it I recommend you to try gunblood. Gunblood is a very good game for free time gaming. If you havent played any games than this is the best game to start. It is very easy playable.
You have to move mouse to your gun and wait the count down. When the countdown ends you move your mouse quickly to your opponent and try to kill him.