When a free browser demo is the right answer
There are a lot of single-page bouncing ball simulators online, and they are genuinely good at what they do. If you want to watch balls multiply in a circle, adjust a slider or two and close the tab, one of those is the correct choice and nothing here improves on it.
The limitation appears the moment you want to keep the output. Most have no recording, which means screen capture, which means whatever frame rate and compression your capture tool produces rather than a clean render. Most have no audio beyond a generic click. Most reset entirely on refresh, so a look you liked is gone.
None of that matters for a two-minute distraction. All of it matters if you are publishing.