Hmm, Steampunk references an era that ends right before 1880, before WW1 and after the American War Between the States. During this era of war line/set piece battles were falling out of favor. Indeed, during the War Between the States, the first half was fought via colonial era type line battles (excepting for the greater range of a rifle-musket of that era VS. the smoothbore of the previous one), which then devolved into WW1 style trench warfare during the latter half of the war. If I were to design a tech tree, I probably would start right before the pike and musket era, back when mounted knights in armor could still be protected from primitive blunderbusses by their steel armor, and end it right at the end of the line battle era, with rifle-muskets, rifled muzzle-loading cannon, steam locomotives, and buoyant airships as the landmark apex technologies. All in all, during the game you would be researching from medieval punk, into steampunk. Of course, I will defer to the fine gentleman who is heading the framework design, but I just wanted to contribute some ideas/suggestions.