It's a web-cam enabled ping-pong-shooting tower, situated in an alien control room, where various aliens are working among light-up targets, which register when you hit them.

You can join a queue to shoot the targets (and the aliens, if you choose), and get about 30 seconds of play time.

It uses flash for the video streaming, it should detect a lack of, but sometimes if the browser interrupts the loading of it it might never trigger as not being enabled.