Why won’t someone think of the children?! Actually, some of the best hacks come from entertaining the little ones. Take [Piles of Spam's] two video game builds. The first is a telescope-based controller that is used to shoot virtual cannon balls at a projection of a pirate ship. The second is a two-player cooperative game where one player drives and the other shoots. Both of them use a projector to display the playing field, an IR laser for targeting, and an NTSC camera to pick up the location of the laser dot. This works really well, thanks to the quality of the physical builds, and great audio and video on the game side of things. See for yourself in the clips after the break.
A couple of posts into the thread [Piles of Spam] talks about laser intensity. He wanted to make sure that there wouldn’t be a room full of half-blind five year olds thanks to the targeting system.