Round 1 - Use W and S to move up and down, press E to shoot the ball, but don't let the goalie catch it. If the ball reaches the goal, you get a point (Your points on left side) if it touches the goalie, the goalie gets a point (Their points on the right side) When the blue cube comes, just let the animation happen, they will shoot 3 times, it's randomized if they score or hit the goalie. Round 2 - Use W and A to move, it's just like round 1, except you are the goalie and the red cube is the shooter. If you touch the ball, you get a point (Still on left side) if the ball touches the goal, the red cube gets a point (Still on right side) Round 3 - Use WASD to move and go to the other side of the field to score a goal. Touch the edge to go to the next area. Note that if the goalie gets 5 points they win.
Credits to Aiden_777 for some ideas though.