Net Paddle!

Air hockey or ping pong like casual game playable with a friend on iOS or Android phones over local wireless network.

In single user mode it is just your reflex against the computer. To play another player on the same wireless network, one player hosts a game, the other player joins as the guest, both are assigned temporary unique names based on IP address.

Game state data is sent using UDP datagrams, encrypted to guard against cheating and hacking, though the consequence of cheating is just a frustrating play.

The host player announces a new game (via Zero-Conf), the guest joins by sending the host a message to host's IP address to start the game.

Each player updates their own paddle position, but ball trajectory and scoring is kept and computed by the host.