The Quest for Perfect Collisions (lisyarus.github.io)

Lovely! I tried to simulate simple orbits when i was a teen. No wonder my attempts were so crappy - it's a lot harder that I thought it would be!

Great read but am sad that the last 'perfect' simulation doesn't have a simulation render in real time (snapshots at fixed intervals such as 1/60 of a second) so that we can marvel its beauty without the slowness of the algorithm.