If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Z - hit ball.
M - hit ball.
Power Swing is a simple game, not frills and fancy packaging just good old fashioned fun! The earlier you swing the harder you will hit the ball, but if you swing too early you will miss! The goal of the game is to knock the other player off the edge of the stage. Good luck!