There is also a DPaint inspired app which can run in the browser.

https://www.stef.be/dpaint/

edit: you can even "Preview in DPaint" which has an embedded emulator!

Stone Tools author here. I did mention that web app twice in the story, though I didn't catch that "Preview" function!

Well that shows how much I was paying attention whilst reading!

Author here. I did not say circles don't draw well. I said that "swiftly-drawn curves are flattened" and likened it to a "large wash." By that I mean long, swift, edge-to-edge brush strokes. Perhaps the use of the word "curves" confused that point, but the natural arcs of human hand/wrist motion are what I wanted to evoke. I also noted a "fat brush in symmetry mode" exhibits the same effect. I can attest to two points about that from firsthand experience:

1. That was also true on original hardware (when I owned the system in my younger days). I distinctly remember having to slow down certain movements to let the system keep pace, depending on speed and complexity of motion. 2. The effect is drastically improved (and I note so in the article) by choosing a faster virtual CPU.

Why would the mouse polling speed mess up the circle drawing itself? You record the start position point (center) and then get the new mouse position and calculate the delta to the start position to get the radius, then draw the circle with the values. Same algorithm.

They did not mean a circle drawn by a circle tool, but instead freehand drawing curved shapes.

Correct. I did not say anything about the circle tool being slow.

Also this older clone: VGA Paint 386 (https://www.bttr-software.de/products/vp386/)

It runs in DOSBox, making it a bit easier (imo) to get running on most computers (and Android devices) than old Amiga software (even if I have FS-UAE and Amiga Forever installed as well on my desktop computer).