Five years ago I had an idea to try creating a mod of MTW for the Harn setting. Like a lot of things, this got put on the back burner, and ultimately I never got anywhere with it. Fast forward five years later, and I'm looking at doing the same once again, but instead with the followup Medieval 2: Total War.
There had been previous concerns about the suitability of doing a Harn Total War, though having played the Stainless Steel mod, and researching how far the game can be mod'd, there are several submods that could make a Harn version fit within the setting.
Stainless Steel has had a sub-mod called RR/RC (Real Recruitment/Real Combat), which categorizes units by type (Militia's, professionals, Religious Orders etc). Different types can be restricted in the amount of recruitment so that you don't have a horde of 1000+ cavalry wrecking havoc across the world. Unit sizes can likewise be adjusted. A unit of "Knights" in Harn might only have 3-5 men in them compared to the default 24-30 as an example).
There is also a SS sub-mod called BGR (Byg's Grim Reality). It puts further restrictions on the player to not only give a challenge, but to limit the ability to expand as easily as you might in a vanilla M2TW game.
Settlements can be restricted in how large they can grow. Most settlements won't reach the highest level of walls, whereas only the cities listed in Cities of Harn (and it's followup) could even have the potential to become Huge cities. This would also inherently limit where troops can be trained from.
I intend to implement the above two submods to properly represent the nature of the Harn setting.
My first step is to get a functioning map working with a few settlements to have something to work with. So far there is something preventing the map from loading properly. I'm on my third attempt.
The map will be 300 tiles wide by 214 tiles high.
The Next Step is to update the height map to represent the geography of Harn.
The Third Step is to update the map to include regions and cities. The limit is 199+Sea region, but I doubt we'd get that many.
Different regions can have varying degrees of rebelliousness. Wilderness areas which are barbarian lands may have constant threats that force a player to devote a lot of resources to quell, which may or may not be worth doing. Rebels can be very active and in some cases have been known to take the initiative and lay siege to settlements.
Once the map is done, work on factions will commence. Decisions on which factions to include will be made at this time. I assume all the major kingdoms, a few Barbarian tribes and a few Religious Orders might be represented. The limit is 31 factions, including "rebels".
Once the factions are done, a unit list will be created to give each faction appropriate units. There is a limit of 500 units. The typical "stack" of 20 units on Normal unit size generally has around 1000 soldiers. I'd expect a typical stack of 20 Harn units on Normal unit size to have perhaps 200-250 soldiers, just to give a perspective on the scope of Harn combat (if this is appropriate).
Finally, the list of cultures/religions (which ever is most appropriate) will be created to best fit the social/political dynamics of Harn.
Below is a sample map I'm using to generate the terrain of Harn: Total War.
This project will require the assistance of those familiar with aspects of the setting which I may lack.
To start I'll be looking for assistance with the following once the project is at the appropriate stage:
Map assistance (geography, trade resources, location of cities, etc).
Faction Development (including descriptions and background)
Unit Roster Development
Unit skins and models (if new ones are needed, though if possible I'd like to utilize existing skins from other mods).