About terrain...
When looking at any historical map with a terrain overlay it's immediately noticeable that historical (and modern) borders tend to follow natural boundaries such as rivers and mountain ranges. Rivers of course have been province borders back in EU1, but mountain ranges are still considered to be part of a province's terrain rather than terrain you need to cross to get to another province.
On my map, mountain ranges that form borders between provinces will mostly be handled with adjacencies, and will only have limited influence on the actual province terrain. Hopefully with 1.3 we'll get adjacencies that combine the defensive bonus of "river" adjacencies with the movement blocking mechanism of "winter" adjacencies. Provinces would then be assigned terrains like so:
- thin grey borders = normal borders
- white borders = rivers and lesser mountain ranges (defensive bonus)
- black borders = mountain ranges (defensive bonus, no crossing in winter)
- red borders = impassable
- green provinces = plains
- yellow provinces = hills
- brown provinces = rugged hills and low mountains
- grey provinces = high mountains
Terrains are assigned based on the areas where most people live and where battles were (or would have been) fought. Consequently, several provinces that largely consist of mountains are considered plains, like Piemonte, Brescia, and Friuli. So when e.g. attacking Piemonte from France, you will get a combat penalty since you will be crossing the Alps, but if you attack from the east then you will be fighting on plains.
In the game, the actual terrain map would of course look something like this (plus rivers):
This is essentially a colour-shaded relief map, and while it looks nice, it's of only limited use for determining province terrains and adjacencies. I've experimented with this a bit and the best I could come up with is to draw another texture onto the relief depending on province terrain. I did something like that with the mock-up of East Asia I posted a while ago; you can see that densely vegetated regions in Manchuria, South-East China and Indochina have a forest-like texture that becomes darker in the tropics, representing rainforest. In this case I based the textured area on potential vegetation regardless of province borders, but simply filling provinces that have a certain terrain would also be an option, similar to the Two Thrones map:
Speaking of vegetation, I'm considering having Victoria-like terrain, i.e. instead of plains, hills etc. there would be steppe, farmland, woodland, arid hills, cultivated hills, forested hills, and so on. On the terrain map these would be indicated by textures. Rivers would of course also be drawn, and mountain ranges could be inferred from the relief. Showing adjacency types on the political map would be a little more problematic since there will be no actual river provinces; I'm thinking of drawing some symbols instead (like on model railway plans) indicating watersheds, passes and bridges.
Another thing I've considered is not drawing province borders at all on the political map except where special adjacencies apply. So the only way of seeing the outline of a province would be selecting it. Not sure if it's a good idea, but it would look nice.
Anway, this is just some general info since there's not really much else to show at the moment. I'm currently working on several different regions kind of simultaneously and once one of them is completely filled with provinces I'll post some new map previews.