During this time, more attention will be paid to medicine, and you can expect this to be reflected in the game. Armies become more armed and armored. The introduction of the feudal system will probably be introduced in the game. Also, this period saw the rise of castles, so hopefully gameplay involving these structures will be included. These two factors should alter gameplay in an interesting way.
Guns get better, ships get bigger, and science begins to take a larger role in things.
Rapid changes abound during this time period. We'll see the use of steam in transportation, and the practical use of electricity. Of course, the US Revolutionary and Civil wars were fought at this time, so it's quite possible that players will get to act out part of these wars. Obviously there are a couple world wars to re-enact, and all the tools to blow up the enemy are included. Yep, it appears that during the later part of this century, we'll fight wars with only our robots.