[aweinstock]

I do think adding a Noita-style cellular automaton would be fairly straightforward.

Currently Veloren has water and lava, but neither will flow (e.g. if water blocks are manually placed on top of a hill, they won't flow downhill, fortunately this is rare due to worldgen). A simple way to fix this would be to have an ECS system that uses CA-style rules (e.g. a water block with an adjacent-and-below air block swaps places with that air block), though naively doing this would be expensive (iterating over all loaded terrain chunks every tick). A possible optimization would be to detect such blocks, remove them from the main terrain grid, put them in a separate entity-with-terrain-collider (the same kind we use for airships), and only iterate the (sparsely populated) AABB of fluids-that-have-recently-moved. This is similar to what Noita does with keeping track of recently-updated terrain rectangles. Once this is in place, it can be straightforwardly extended with more fluid interactions (e.g. Minecraft-style water + lava = obsidian, more Noita-inspired gases rising).