Would be interesting if you could build radioactive dirty bombs. Nothing huge, but enough to create a small radioactive area that would last a few days (in game). Could be made with a small amount of very hard to find and uncraftable radioactive material. Yes it has awful griefing possibilities, but could also be used for defense. Imagine tossing one through someone’s window and irradiating a small section of their base for a couple of days, or out of your window when people are attacking.
I forgot the ingredients! Some cloth, gunpowder, rock, radioactive material, and those empty bean cans!
EDIT: Oh, and if not dirty bombs I’d rather see grenades like this. Would be fun to light the fuse and time when you throw, even allowing the possibility of grenades thrown early to be picked up and tossed back.