Astronomy
Eccentric Orbit (e=0.85)
M = E − e·sin E, e = 0.85

A wildly eccentric orbit: the body whips through a tight periapsis and crawls out to a distant apoapsis, sweeping equal areas in equal time via the library's Newton solver.
Computed & rendered in pure C# on the frozen OnlyCSharp 1.8 library — animation baked to GIF with the library's own
Gif encoder (no GPU, no ffmpeg, no external packages).