First off I think it's a great addition to the world. It makes it seem much more alive and reinforces idea that the planet used to bear some sort of more advanced human civilization in the past.
1. Rivers that "branch" out currently do not generate those branches when you settle on them
I guess this an oversight since roads have intersections when generated. In any case it should be represented when settling there.
2. Rivers going through mountains shouldn't really have overhead mountain on top of them
While underground rivers exist I don't think it makes sense that every river going through mountain is one. I think there should be no overhead mountain at all, instead the river should "carve" a small valley into the mountain; so basically you have the mountain to the side, then 1-2 tiles of mountain-ground and the river in the middle. The side mountains would have 1-2 tiles thin-rock roof and then overhead mountain.
3. The effect of roads on movement should be immediately visible
While you can see the benefit while traveling on your pawns, the tile description should show the effect of roads on movement.
For example:
"Current Movement time: 1 hour (road: 0.5 hours)" (added to existing line)
or "Current Movement time on road: 0.5 hours" (new line)
4. Rivers should impact movement
Just like roads, rivers should impact movement. The larger the river, the slower it should be to cross the river. With the exception of a road leading across, that should nullify any penalty and just give the road bonus. For the biggest of rivers perhaps even impossible.
5. Different impact of road types versus biome/tile type
Right now it seems any type of road just halves the move speed time by 50%. While I appreciate the bonus, I don't think it makes any sense that a dirt road (which resembles a road barely) has the same impact as some ancient highway that is still somewhat intact.
In addition I think the road's impact should be bigger depending on the terrain type. Basically flat terrain is already easy to traverse, so moving along a road here shouldn't have a big impact, while mountains are extremely difficult to traverse and since the roads tunnel right through the mountain tiles the impact should be very significant (bringing down from 12h to 2h for example).
It's a similar case for biome - when you think about traversing a forest for example, traversing a road instead should be much easier since there is not much stuff in your way. Even when the road isn't in the best shape, i would be still much easier then going right through the forest.
So to implement that I think it would be better to give traveling along a road a new base cost instead of using the terrain/tile cost and then adjust it depending on the biome/tile instead of the other way around, so for example:
A highway could give a base movement time of 0.25days (being the most intact and "best" tile), while a dirt road only gives 0.9 days (being barely better then no road).
Those days would then be multiplied by tile, again for example:
That would still only be 0.5h on a highway in a mountain, but I think it's reasonable. You have tunnels bypassing the highest mountains avoiding a lot of climbing and difficult traversal, and only have to deal with having to travel upward at some point (and downhill at another) and being careful. Hills the same story, but to a lesser extend of course.
Temperature should probably have a higher impact then biomes: snow&ice obviously would be very hard to traverse as would be traveling through blazing heat, as it would be very taxing on the pawns and animals.
Biome next thing, since temperature is already covered I think the impact should relatively low, if any at all.
Overall the result would be a much lower travel time on roads. I can see this might be a bit too strong, but I also have an idea to offset the benefit of the roads. I'd make it so that you're much more likely to be attacked by raiders while you are on a road, thus while it would give you the benefit of getting everywhere much faster, you'd also be taking a risk of your caravan being raided. That you have a higher chance to be raided should probably be reflected in a tooltip somewhere (perhaps on the tile tooltip when you hover over the "dirt road" etc)
1. Rivers that "branch" out currently do not generate those branches when you settle on them
I guess this an oversight since roads have intersections when generated. In any case it should be represented when settling there.
2. Rivers going through mountains shouldn't really have overhead mountain on top of them
While underground rivers exist I don't think it makes sense that every river going through mountain is one. I think there should be no overhead mountain at all, instead the river should "carve" a small valley into the mountain; so basically you have the mountain to the side, then 1-2 tiles of mountain-ground and the river in the middle. The side mountains would have 1-2 tiles thin-rock roof and then overhead mountain.
3. The effect of roads on movement should be immediately visible
While you can see the benefit while traveling on your pawns, the tile description should show the effect of roads on movement.
For example:
"Current Movement time: 1 hour (road: 0.5 hours)" (added to existing line)
or "Current Movement time on road: 0.5 hours" (new line)
4. Rivers should impact movement
Just like roads, rivers should impact movement. The larger the river, the slower it should be to cross the river. With the exception of a road leading across, that should nullify any penalty and just give the road bonus. For the biggest of rivers perhaps even impossible.
5. Different impact of road types versus biome/tile type
Right now it seems any type of road just halves the move speed time by 50%. While I appreciate the bonus, I don't think it makes any sense that a dirt road (which resembles a road barely) has the same impact as some ancient highway that is still somewhat intact.
In addition I think the road's impact should be bigger depending on the terrain type. Basically flat terrain is already easy to traverse, so moving along a road here shouldn't have a big impact, while mountains are extremely difficult to traverse and since the roads tunnel right through the mountain tiles the impact should be very significant (bringing down from 12h to 2h for example).
It's a similar case for biome - when you think about traversing a forest for example, traversing a road instead should be much easier since there is not much stuff in your way. Even when the road isn't in the best shape, i would be still much easier then going right through the forest.
So to implement that I think it would be better to give traveling along a road a new base cost instead of using the terrain/tile cost and then adjust it depending on the biome/tile instead of the other way around, so for example:
A highway could give a base movement time of 0.25days (being the most intact and "best" tile), while a dirt road only gives 0.9 days (being barely better then no road).
Those days would then be multiplied by tile, again for example:
- 0% for flat
- 25% for small hills
- 50% for large hills
- 100% for being on a mountain tile
That would still only be 0.5h on a highway in a mountain, but I think it's reasonable. You have tunnels bypassing the highest mountains avoiding a lot of climbing and difficult traversal, and only have to deal with having to travel upward at some point (and downhill at another) and being careful. Hills the same story, but to a lesser extend of course.
Temperature should probably have a higher impact then biomes: snow&ice obviously would be very hard to traverse as would be traveling through blazing heat, as it would be very taxing on the pawns and animals.
Biome next thing, since temperature is already covered I think the impact should relatively low, if any at all.
Overall the result would be a much lower travel time on roads. I can see this might be a bit too strong, but I also have an idea to offset the benefit of the roads. I'd make it so that you're much more likely to be attacked by raiders while you are on a road, thus while it would give you the benefit of getting everywhere much faster, you'd also be taking a risk of your caravan being raided. That you have a higher chance to be raided should probably be reflected in a tooltip somewhere (perhaps on the tile tooltip when you hover over the "dirt road" etc)