It was the latest in a long line (I've lost count!) of seminars we've given to people of all ages who are keen to learn all about Arduino and what you can do with it.
I whipped together a simple multiplayer game in Processing, and dubbed it 'BirdWars'. Each player controlled a simple shape, using their analog joysticks to control the heading of the shape, and the controller buttons to accelerate, decelerate and fire.
We spent the best part of the day covering the constituent parts of the controller and the programming that is required to enable that, and spent the last half an hour of the day playing the game.
Attendees were given an EtherTen as well as an input shield that consisted of a joystick and five buttons. We got them to add a speaker and a 'rumble pack' in the shape of a vibrating cell phone module.
When players collided with walls and were shot, the pack would rumble. When they fired their weapons their speakers would chirp. They also added a RGB LED that displayed a colour that reflected their health and fuel.
We allocated each player their own unique address on the network, and after they faithfully set those addresses, the thing worked like a charm! We had all 16 players in the game having a great old time.