Love the interesting density stratification and the little bubbles that move around. Very foamy or multi-fluid looking.
Not sure if it's intentional but the fact a click/touch only sort of locks the nearby particles is very satisfying. The fact I can slowly absorb particles into the click region, that the particles still engage in the slow, sticky motion and evolve inside the region and that I can then fling them off is bizarrely good.
Sure it could use a bit of optimisation and tweaking to make it move and look more like a fluid but I think this is a fantastic proof of concept of this particular method as an online, interactive example.