New submitter schirra writes "Researchers at MIT Game Lab have created a free video game that accurately simulates the effects of Einstein's relativity. 'A Slower Speed of Light' challenges players to collect objects strewn throughout a level to artificially lower the speed of light. As light speed slows to walking pace, it makes visible the unusual effects one encounters when traveling close to the speed of light, such as the Doppler effect, searchlight effect and Lorentz transformation. The effects are, in a word, trippy. The team plans to release an open-source Unity3D toolkit called OpenRelativity to allow others to include the same relativistic effects in other games."
They also plan to release the source code sometime next year (despite reports that it is open source already).