Paddle Ball
The classic two-paddle arcade duel. Return the ball past your opponent; where it hits your paddle sets the angle, and every rally speeds it up. First to 11 wins.
One player: you are the cyan paddle on the left. Move it with the mouse, by dragging on the court, or with W S or ↑ ↓. Two players: left uses W S, right uses ↑ ↓; on a touch screen, each player drags on their own half of the court. P pauses.