Player 1 is red - use the arrow keys to move, and 0 to shoot - remember to turn on the num lock! It is hard to hit the other character - but use your choice of shot well - if you miss then you lose a point. Same rules apply for player 2 which is red, but use WASD to move and e to shoot - finally, if you touch the other character, you both lose a point. You lose on 0 points. Good luck!
I made it by using the little block thingys.