If you’ve read a lot of SF then you’ve probably read at least one scene where the protaganist is on a spaceship going an appreciable fraction of the speed of light – fast enough that they start to get the Doppler effect happening on photons, and see the colors of the stars start to change.
This game reverses the situation: as you play it, the speed of light gets lower and lower, so you can see the crazy rainbow effects happening at a running pace. There’s not much of a “game” here – just 100 objects to collect. But I had a lot of fun just running around watching the world change, and maybe even getting an intuitive understanding of what it’s like to go close to the speed of light.