My favorite is 'spongy', an underwater journey through a Menger-sponge fractal in 128 bytes:

https://www.pouet.net/prod.php?which=53871

https://www.youtube.com/watch?v=36BPql6Nl_U

I'm more impressed by the eerie beauty of it than the technical achievement, even if the code was orders of magnitude larger it would still be wonderful.