One of the problems with simulating battles like Antietam is that it’s hard to build in balance to what was an imbalanced scenario, made even through human error and circumstances at the time.
Any gamer who’s given control of the Union army at Antietam and is able to launch a co-ordinated attack should in most instances account for the Confederate forces on the field. The preponderance of numbers is simply too great. It’s a similar situation with Chancellorsville – any gamer who found themselves in Joe Hooker’s shoes prior to the moment he lost confidence in Joe Hooker on May 1st, isn’t going to make the same mistake. In order to simulate the 11th Corps being routed you’d have to start the battle with federal forces being fired into and already starting to rout, as otherwise you’d have every union player right facing and preparing.
You need battles where forces are relatively evenly matched, and the players are given a fair bit of tactical flexibility – battles such as First and Second Bull Run, Stones River, as someone has mentioned – Chickamauga could be an option as well. Chattanooga perhaps? Lots of little scenarios and what-ifs that could be employed (Longstreet isn’t sent to Knoxville, Lookout Mountain is reinforced, etc ).
Personally I’d love to see Shiloh. Either way though it’s a fantastic game, and very enjoyable, and I look forward to further offerings from the team.