Net Paddle is an air hockey or ping pong like casual game playable with a friend on iOS or other smartphones 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 between host and guest, encrypted to guard against cheating and hacking, though the consequence of cheating is just a frustrating play. Each player updates their own paddle position, but ball trajectory and scoring is kept and computed by the host.