I find most of my breakthrough moments when thinking of D&D come to me in the shower.
Anyway, I mentioned in a post before that I thought the Xbox game Gears of War was a pretty cool game, and also that I thought it would make a interesting D&D style rpg. I beat the game today and sat down to start working on making that Gears of War D&D game. Almost immediately though I started running into problems. So much of the gameplay relies on gunfighting, and although it is a very gritty brutal and almost medival setting there are still many hightech elements. All these hightech guns and vehicles and stuff would be difficult to convert into an oldschool D&D system and I wasn't sure where to start or even if I wanted to. I started feeling pretty discouraged about the whole thing.
Then it came to me in the shower. Why not just get rid of the guns and transplant the whole thing into a Dark Ages type setting? BAM! Kind of obvious now in retrospect actually. Here are two pictures, concept art for Gears of War.