My 13 yo daughter introduced me to Scott Westerfeld's Leviathan series which is a Steampunk world where WWI is fought between the Clanker's (German war machines, ships zeppelin and planes) and the Darwinists ( British genetically modified creatures for land, sea and air battles) It is an amazing world, and would fill a similar niche as the new D&D system with land and air battles. It would attract the steampunk era and fans do this great book series.