This is the only kind of thing that would make me think of a giant crack nuke..... kinda like that Jamaican guy on all the T-Shirts who has crack. (No offense to anybody who happens to own those shirts!)
In any case, I've been watching him make this sim, and it's really good. I do have an idea, though: Why not make a sky box effect when you drop the nuke. Start out with two skies, one being a Happy Sky or something, and a 0% opacity Cloudy Sky. When the nuke drops, switch out the sky boxes using the opacity settings, and voila!
That, and try adding on an Autogun or something.... and by autogun, I mean an Auto-Targeting gun turret or a similar weapon. It'd be hard to make, but it would be so frickin' sweet.
Anyways, great job, man. It really turned out nice.