HiPhyEngine is a new and original multi-solver physics addon for Blender.
“Multi-solver” means that it can simulate various types of material such as rigid bodies, soft bodies, cloth and even particle-like physics such as snow or sand.
Compared to built-in Blender physics, the addon tends to be a bit slower. In exchange, the simulation is a lot more stable, meaning that for example your cloths sim will not intersect or explode for unknown reasons.
Another strong point of the addon is that the various simulation types can interact with each other natively.
Overall, my experience is that in exchange to being stable (e.g. cloth simulation doesn’t explode or collapse like the built-in Blender cloth), HiPhyEngine is … slow. I’m sure it has its usage cases but for me the speed is a deal-breaker. Hopefully, that will improve in the future.
However, HiPhyEngine is not all about cloth simulation. The Sand and Snow simulation are unique features that don’t really have a strong alternative in Blender.