What about a micronuke? It would be 10 times smaller and be thrown like a grenade, causing a tiny mushroom cloud only like 2 or 3 minifig-heights tall. It would have a large kill radius but to scale with the projectile's size.
Then a nanonuke! Then an attonuke! A piconuke! A yoctonuke! The yoctonuke causes an explosion the size of a 1F pole brick.