http://www.ultimategeneral.com/
(http://static.squarespace.com/static/51cabf8ae4b043b66a22b6b9/t/51ccd4c6e4b0814177bac9f3/1372378313752/UG_2.jpg?format=1500w)
A game made by the creator of RTW's DarthMod, focussing specifically on gettysburg but they might later edit the engine to do other battles of the era too. :)
It looks pretty interesting, I'm keen to see more information on how it's going to work; the idea of making a couple of Guns, Swords and Steam battles in it has occurred to me if modding is easy :)