Air hockey is a great alternative to real hockey if you don't have access to ice and a stick. Likewise, Air Hockey Challenge is a great alternative to air hockey if you don't have access to a air-pumping table and one of those plastic paddle things.
Air Hockey Challenge is definitely the best air hockey game I've seen for Windows Mobile. The purpose of the game is to score goals by whacking the puck with your paddle, while guarding your own goal. You can play against the PDA or set up a networked game over Wi-Fi. There are three different single-player modes to choose from (Traditional, It's a Knockout, and Against the Clock). You can also pick between three difficulty levels.
Playing Air Hockey Challenge is great fun, thanks to its realistic game physics and sound effects, as well as interesting power-ups and particle effects. It's dead easy to control and merely involves holding and dragging the puck around the screen.
On the downside, there's no music (not even in the menu screen) and this demo version is a little too short for my liking, only allowing around a minute of gameplay each time.
Overall though, Air Hockey Challenge is the best of its genre for fans of the 'sport'.