I assume a software like Paraview was used to reconstruct a surface of the particles, and then some material was applied. Paraview has a "SPH Volume interpolator" that's very useful for this in combination with the Sheppard summation

I use corona image editor for most renders from any other things I use, myself. The tool came with one of the cracked corona renderers I use for C4D or . Only for my own amusement, though, I did end up having some skills after years of that little 3Ds max. Other than that, luxrender is a wonderful renderer way better than cycles or anything else for many things, it's really free for Blender it's called Luxblend, it has built-in very good post processing options. Other than that, a lot of other cr4cked renderers over the years. I will never ever use it commercially, though, so it's fine, I just love it it's all and I can't stand the limited freeware versions. For Blender I use K cycles and Ecycles X pro. K-cycles has built-in post prossessing. But I don't know if that was your question. Fluid sims I just use Realflow, mantaflow, other advanced fluid simulations that I don't have anymore, etc... Or is this all real time? Because there's really not many particles. It kinda look like that Nvidia flip fluid demo I found a long time ago, that's probably still around and not used by any games ever, or very rarely.