Super cool shader toy! Semi-related, but my favorite demo ever (a tiny 64k Heaven Seven[1]) was fully coded in extremely esoteric assembly and used all kinds of mind-blowing tricks. There's a blog post written about it somewhere by a few Exceed members; real-time raytracing on a CPU in 2000 still blows my mind.

[1] https://www.youtube.com/watch?v=rNqpD3Mg9hY