I've been toying with the idea of trying my hand at a 1400AD campaign.
The 15th century was an immensely interesting period historically speaking. Heavy plate armour is arguably at its peak. Cannon starts seeing real use in European battlefields. Wales is finally annexed by England. The hundred years war is at its height including the Battle of Agincourt and Jeanne D'Arc. The War of the Roses follows some time later. Constantinople falls to the Ottomans (sadface). The Golden Horde breaks up. Rodrigo Borgia becomes Pope and the Italian Wars begin towards the end of this century. Christopher Columbus lands in the Americas. The list goes on...
I did some looking and managed to find a geopolitical map that more or less covers the Stainless Steel campaign map circa 1400AD.
https://www.euratlas.net/history/europe/1400/1400.jpg
Most of this can be done, I think, by taking a Late Era SS campaign and updating the starting cities for various factions in 'desc_strat' and also updating 'desc_events' so that everything pre 1400 has already occurred. Might need to also update some city/castle sizes so that they're big enough to field the later tech? (I don't think any citadels even exist on the campaign map at the start and I believe those are necessary for the later era elite troops). I'd also probably make it at least a 4TPY campaign if not 12TPY, since at this point we're starting almost 200 turns after a late campaign would normally begin using SS's 1 turn per year.
Lithuania is gone by this point, and Norway, Sweden and Denmark have merged into the Kalmar Union, which frees up at least two faction slots. If a 3rd faction slot were really needed, doomed Constantinople could probably be made a rebel city at this point (painful as that is to say as a byzantine fan). I'm not wholly sure who best to add with those freed up factions however, probably Wallachia off the top of my head so Vlad can do his thing. Modding new factions isn't something I've done before, so it would definitely be a learning experience either way and would probably just consist of copying rosters for existing factions (Denmark for Kalmar, Hungary for Wallachia).
Just idle musings on a rainy morning. Any thoughts/advice would be appreciated.