This game can be played by 0 to 2 players.

Pressing W/S will activate player 1, and also move the left paddle up/down.

Pressing Up/Down will activate player 2, and also move the right paddle up/down.

Pressing neither of those will let the CPU play against itself, which can be interesting to watch
as well.

F1 ... Help
F5 ... Hint for power ups