I love this site, the method is very clever. I did a re-implementation of this at one point for fun. One of my favorite things to do with this simulation is to

I love this site, the method is very clever. I did a re-implementation of this at one point for fun. One of my favorite things to do with this simulation is to actually plot the path of the photons as they approach the black hole (well, leave the black hole but you reverse time for ray tracing purposes). Conveys the idea pretty well that there's something funky going on with spacetime. E.g. here https://imgur.com/OPHLMJL https://imgur.com/OPHLMJL (just a screen shot from back then, it's much more fun with sliders that led you move things around).