Minecraft recently added rain, but I think it's mostly aesthetic at the moment. Your thoughts on flooding and erosion might make for an interesting mod. Also,

Minecraft recently added rain, but I think it's mostly aesthetic at the moment. Your thoughts on flooding and erosion might make for an interesting mod. Also, some things do collapse when you might under them. Namely, sand and gravel. It might be interesting to play with making other types of terrain collapse if there's enough weight and not enough support around. I have no idea how difficult that would be though since I've never looked very far into modding Minecraft.