Be prepared to bend time and space, as MIT Game Lab has created 'A Slower Speed of Light', which explores Einstein's theory of special relativity by allowing the player to travel at the speed of light in a game world based on real physics.
The premise is simple: go around collecting a series of orbs in the world around you. However, as you pick them up, the speed of light will reduce incrementally. The result of this (if you were listening in your physics lessons at school) are a few different effects from travelling at near-light speed.
Firstly, the Doppler effect will cause objects moving away from you to shift to the red end of the spectrum, and those moving towards you to move to the blue end. This is due to the change in frequency of light waves, caused by your relative movement to it (think of sirens on a passing emergency vehicle passing by, that's the same principle). Move ever closer to the speed of light and you begin to see progressively strange effects: time dilation (the world slowing down around you as your experienced time begins to differ from everyone else's), and Lorentz Transformations (objects around you will warp and change shape, as the distance between objects appears differently at relativistic speeds).
This game works well as both a fun experimental hour of playtime and a learning tool for relativistic theory. Beyond this, MIT Game Lab also welcomed the OpenRelativity engine with this game. Simply put, developers can also implement the simulated effects of travelling at the speed of light with this set of tools.
Be sure to download your free copy of this. Simply fascinating.