Play here
PongNM stands for Pong Not iMproved
Open index.html to any modern browser, set your preferences and just play. You can play human-vs-human, human-vs-pc and pc-vs-pc. On human-vs-pc, regardless of which side you choose for yourself, the opponent is going to use the AI level indicated by the "First AI Level" selection.
Controls are up-down arrows, in single player mode, while in human-vs-human player 1 gets the key 'w' for up and the key 's' for down, while player 2 gets the arrows.