Here is my submission for the challenge.
Sadly I don't have the time to work on it again before the end of the month, and the AI is stupid to say the least.
The twist is pretty straightforward, the arena is round instead of rectangular.
When a player hits the ball it changes its color. When the ball is red if it exit the arena the point will go to the red paddle. Viceversa when it's blue the point will go to the blue paddle.
The two paddles can also overlap and both hit the ball. When this happens and the ball exit the arena a point will be subtracted to both player.
Here's the blog post:
I hope you like it
Code reviews are really appreciated!