Gave it a lazy try on Monarch, basically defending from the forts and occasionally attacking the leftovers.
1912AD by a Rifleboy.
While all was going well I did try how far ya can go.
Unbelievably that Rifleboy has smashed about every type of unit in the game! Main issue since getting the Rifle at lvl 10 was making sure fucking Zara Yaqob was stopped destroying me tile improvements.