I'd say the map of rome 2 has a similar size to mortal empires that said CA has said that there will be a warhammer 3 that will increase the map even further. Total War: WARHAMMER II - Mortal Empires is a free game for Windows that belongs to the category Action, and has been developed by Creative Assembly.

In Warhammer, you can pick who you fight for and there are tonnes of factions (small organised groups within larger ones) that you can pick from.

It should be noted that Mortal Empires is so grand in its epic scope that CA had to sacrifice at least one thing. For those that have missed any Mortal Empires news up to this point, it combines (most of) the New World, with the full Old World map from Total War: Warhammer. AtWar, formerly Afterwind, is influenced by Strategy war games like Risk and Axis & Allies.