...might be possible to adapt it to sand also. It is not very likely as there are some short cuts I can take with water to make it feasible that will not work with things like sand.
Haha sorry about that. I meant how would it be possible to make sand also react like a fluid, if that is the direction you choose to go?
I hate to be the one that brings up Minecraft, but I find the water physics irritates me to hell (read: stickler for realism). Is it likely to be done in a similar way? I assume not, as that model would not work with sand very well.
The plan is to simulate water with sort of particles. It requires some heavy data management and the rendering may become infeasible. The goal is to be able to do things like drain mountain top lakes if you punch a hole in the bottom or have cascading waterfalls that can still be deflected by user created objects. It's complicated.
Flowing sand may be better suited for a cellular automata approach like Minecraft uses for water but the trick is knowing when sand has drained. It's possible that when I implement the water that a combination of cellular automata and fluid particles together will make for sand that drains and flows while still stacking into nice piles on the floor.