Click on the green flag to start. Press "P" for a point battle (first to 7 and win by 2) or "T" for a timed battle (90 seconds with no sudden death). Player 1: Press "W" to go up, "S" to go down, and is 1/3 faster Player 2: Press "⬆" to go up, "⬇" to go down., and is 1/3 larger.
Link to my "1-Player Pong" game here: scratch.mit.edu/projects/249440080 for a fun single-player pong game.