The behavior of light may seem static and uninteresting (it's bright and fast, we get it), but there's actually an incredible amount of science going on that we generally don't experience during our normal lives.
A Slower Speed of Light, a new open-source game for PC and OSX from MIT Game Lab, explores the more intricate and interesting behaviors of light in a "relativistic game engine." As players collect objects, the speed of light is slowed and players are able to experience phenomena such as the Doppler effect, time dilation and the Lorentz transformation, among others.
While the open-source aspects of this project are not yet available, the plan is to release the game's Unity3D-based engine as OpenRelativity sometime in 2013. For now, the game itself can be downloaded here.