Serve: tap the ball / Space to strike it on the power bar. Aim for the green band; too much power flies it over the bar.
Rally: if a shot misses the goal (or is saved) the ball ricochets back toward the other goal, faster each bounce — until a net is breached.
Save: as the ball reaches your goal, tap the JUMP button / Space (or F for the left goal, J for the right) to time your keeper's jump. Don't jump at low balls — the ball slips under.
When a ball enters a net, the other player scores. First to 5 goals wins.