W and S for player 1
press E to shoot a projectile for player 1
upArrow and downArrow for player 2
press leftArrow to shoot a projectile for player 2

to set the difficulty:
1: easy
2: medium
3: hard
4: IMPOSSIBLE!!!!!!!!! 
5: 2 player
6: demo mode

once difficulty is set, press space to serve the ball!
after a point is scored, press space to serve the ball