Player 1 is red, Player 2 is blue. Player 1 moves with up and down, Player 2 moves with W and S. Set the Play To: variable to anywhere between 1 and 25. After you fill in the player's names, the ball will move automatically. Move to bounce the ball onto the other player's goal (your similar-colored line). It's not the exact same color or else you would get a point every time the ball hit your paddle. I have a 1-player version if you want to play against a CPU.
The 2-player version of my other ping-pong game.