Hey, I’ve just released Anima:

https://matthodges.itch.io/anima

Anima is a sandpit in which thousands of particles flock, orbit, and drift in real time. Pick a preset or make your own - add forces, spawn zones, and modulate parameters with LFOs, or turn on evolve to allow settings to wander. Sit back and watch behaviour you couldn't have predicted emerge.

Built on WebGPU.