If you have five spare minutes, Pong Friendly will fill them. Everything happens on one screen with first to 5 goals, paddle at 26% of screen height, and the whole thing runs straight in the browser - no downloads, no sign-ups, no fuss.
Ball speed climbs on every paddle hit, and the return angle depends on where the ball meets the paddle, so control is about position, not timing alone. Spin from a moving paddle bends the return, and that is where rallies get mean.
Nothing here needs a tutorial or a wiki. Controls are one gesture, the goal is one sentence, and the difficulty comes from execution rather than homework. That is exactly what a browser game should be.