A Slower Speed of Light is a freeware video game developed by MIT Game Lab that demonstrates the effects of special relativity by gradually slowing down the speed of light to a walking pace.

[1][2] In A Slower Speed of Light, the player controls the ghost of a young child who was killed in an unspecified accident.

[4] Entering the portal will open a tab explaining the effects of Special relativity, and will also show the time the game was finished in.

[1] These effects include the Doppler Effect (red/blue-shifting of visible light and the shifting of ultraviolet and infrared into the visible spectrum), the Searchlight Effect (increased brightness in the direction of travel), Time Dilation (difference between the passage of time perceived by the player and the outside world), Length Contraction and Terrell Rotation (the perceived warping of the environment at near-light speeds), and the runtime effect (seeing objects in the past because of the speed of light).

[2] A Slower Speed of Light was developed in hopes of being used as an educational tool to explain special relativity in an easy-to-understand fashion.