I'm currently playing as my new favorite faction: Vladimir-Suzdal (since the update, I've started a campaign with Yemen, Vladimir, and Kara-Khitan), as the history of that faction is familiar to me more so than others. The conquest of Volga-Bulgar was too easy in my opinion, and the conquest of the Kypchaks has been arduous; I've destroyed thousands of their men, achieved victory after victory, killed their king and prince, yet have only been able to conquer 2 of their cities. They recruit at crazy speeds! I think Kypchaks are well done and balanced with the current version, although playing as them seems near impossible, as spreading Tengriism is really difficult.
Some things I'd really like to see to further improve the northwest part of the map is to make Volga-Bulgar stronger, add Kievan Rus as a faction, and my dream is to see Hungary be a faction in BC some day. A shift to the west just enough to have Budapest (or at least Pest) on the map would be a dream come true. Having another Latin Catholic faction, I think, would be a great addition to the campaigns of Rome, Kypchaks, Vladimir, and Kiev, if it were to be added. Imagine the West-Northwest part of the map having Latin and Orthodox Christian factions, fighting with Islam and Paganism. The religious turmoil would be wonderful for players. (Although I do acknowledge moving west would be a bit against the point of BC)
Currently, only 26 factions are being used of the 31, so I think sparing 2 for Hungary and Kiev wouldn't be a waste. I also think those 2 factions are vitally important for a more accurate gameplay of Rome, Vladimir, and Kypchaks. I'd be more than willing to get the ball rolling by myself by making Kiev a clone of Vladimir, and Hungary a clone of KoJ with different colors, and extending the map to the west to compensate. Unfortunately, my skills end at 3D art, units, and the more complicated modding aspects, like voice, AI, and balance. The width of the map_heights is also 841, which is smaller than it could possibly be, if I remember correctly, so the map could be exactly the same with an addition to the west.
Is anyone else interested in this? I guess it's just a basic cloning of existing factions, a larger map, and a couple of tweaks with Vladimir, Volga, and Kypchaks. I also had an idea for religion for Tengriism. I was thinking of a building that is somewhat similar to monasteries that Vladimir has, but have them available earlier on. Instead of increasing Tengriism in the region, it could be like -4%/-7% growth of other religions (so missionaries would be significantly less effective in regions that have those buildings). Having Tengric (is that a word?) missionaries and converting effectively both in home and foreign wasn't accurate at all, but before the Mongol (and later Russian Empire) conquests of the area, the best Christian missionaries could do was establish a minority.