A free mod for Mount & Blade II: Bannerlord, by NinjasAndSuch44.
Here it is, my slap-dash messy attempt to make a Byzantine mod. It's approximately balanced, probably won't crash your game, and almost certainly just as erroneously not-byzantine as the original flavour to anyone who's actually academically invested in the byzantines, but hey, there you go.
Installation
Unzip the file and drag it into
C:\Program Files\Steam\steamapps\common\Mount & Blade II Bannerlord\Modules
Once done, enable it from the game launcher
Looks
Maybe it's just me, but I felt that the Empire roster was the only one that felt less like an analogy of its real world nation/culture, and more like a fantasy faction that was inspired by the Byzantine Empire. All the byzantine tropes are there, but the infantry art design always stopped short of actually looking properly like I imagined a byzantine soldier to look. I think it's the over-reliance on that nasalhelm, but I also felt there just wasn't enough of that eastern flair.
So yeah, there's more scale, more lamellar, more eastern influence. There's less of a reliance on those big expensive looking nasalhelms being distributed to every rung of society. At the same time, there's more helmets overall, even within the recruit and early archer troops, as helmets would have been the first thing someone would buy when going off to war.
