You are the blue player. Use WASD or arrow keys to move around. Don't touch the brown sides because they are out of bounds. Score goals against the goalkeeper. To steal the ball from your opponent, you have to touch to tackle and recover the ball.
This took 2 days to make. There are some glitches which I will fix. One glitch I won't fix is when you tackle the ball, then it might go to a random goal.