Filterforge 6, tweaking “Medieval House Walls” (by Totte) filter for the game.
This has a lot of potential for re-use, in particular I think that setting “wall roughness” to zero gave the plaster a much more realistic texture than it has by default.
Here’s screenshots of the settings:
There are settings below “wood dirt”, but I didn’t touch those (except setting “seamless”), the defaults ought to do.
Wall color: B5C7D0