A Slower Speed of Light is a free little game from the MIT Game Lab. It visually demonstrates the effects of relativity. You move around in the first person picking up orbs which slow down the speed of light—the effect being that your normal walking speed inches ever closer to light speed. When you move faster—or light moves slower—colors begin to morph as the invisible shifts into the visible spectrum, until finally time and space themselves start bending. Very trippy, but based on real physics.