It's a very old one, a previous patch has broken the representation of rivers deltas, here is an example with current build (1.0.8.4)
And here is how it used to be before (screen is from Nov. 2016, rivers visual representation have changed multiple time since, it's just to show that it was possible to do nice-looking deltas with the game's engine)
And here is how it used to be before (screen is from Nov. 2016, rivers visual representation have changed multiple time since, it's just to show that it was possible to do nice-looking deltas with the game's engine)
