You are Red. Your swimmer has the yellow arrow, and it swims for the ball by itself.
When you have the ball, press Pass to throw it to the teammate with the yellow ring and PASS under them, or Shoot to shoot at Blue's goal. Get close to the goal before you shoot.
Tap the water to swim somewhere else. Swim into a Blue swimmer with the ball to win it back.
First to 5 goals wins.
Keyboard: arrow keys to swim, space to pass, S to shoot.