Water Volleyball

The game features two players shaped like balls with tiny bodies who hit the ball with their heads.
The game is played from a side-view perspective, and the ball can be bounced off of the walls and ceiling without penalty.
The first player to reach 11 points wins. If the score reaches 10 apiece, then it is first player to overtake by 2 points or first to reach 15 points.
The player may hit the ball only three times in a row.
The game can be played with internal offline trainer or with a random human player via internet (network bandwidth matters).