Thing is, Guilds are rewarded fairly randomly. Yeah, of course, we can edit the way guild points are granted, but that would affect all factions, and not only the skaven one.
In vanilla game for example, Merchant Guilds are fairly common (to the point where nearly every city will be offered one), while some other like Theologian, Explorers or Macons, are hardly ever seen if you don't know what are the requirements.
Hence why I decided to make exclusive, yet non guild buildings. It allows us to limit each city to one clan (two in fact, a warrior clan + a major one, but then, all major clan hire slave and clanrats from Warriors Clans, so that's not really an issue here), and to still use guilds as special gifts/rewards.
Ultimately, and since the only person I'm in contact with is Bwian, I'm awaiting his opinion on the whole tech tree.
I'm currently trying to come up with some skaven equivalent for farms, academy, ports and blacksmith, if you have any idea, you're welcome ;)
Edit, since I just read Bwian's answer.
Yeah, I'm well aware there's a limit to the amount of buildings available. Most of those would be based on vanilla buildings, but with different descriptions/pics, depending on factions' culture.
The only new building planned would be the four clan specific ones.
Bookmarks