[Macuyiko]

Very interesting, indeed, they seem to be driven by better fluid simulations... remarkable that they find their way into games. I was always under the impression that Navier Stokes was hard in 3d, but it does seem like there are performant solutions now that are easily offloaded to the GPU, e.g. https://github.com/chrismile/cfd3d (and NVIDIA also has some blog posts about it).

Edit: I also just found this: https://www.youtube.com/live/569oSOSoKDc?si=8V5buRMoI3IKqLQp... -- which is very close to what you describe and fully matches the kind of particle systems I was hinting at, thanks!