The prospect of adding more realistic mountain graphics as large immovables on the map was raised by Astuur in the Graphics Forum (https://wl.widelands.org/forum/post/4677/)
" We have neither mountains nor rivers in the map. What we call mountains are hills at best, because the editor forbids real steep and spiky mountains. And our "rivers" are .. hmm -- fjords maybe.
While all of this does not matter for playing the game, I could imagine that having some steep mountains would definitely make the maps look better.
They could be placed on regions that now have snow terrain and be bitmaps, possibly derived from fractal paintings, ready for placing them on the hilltops inside the editor. By ready I mean that they should already have a gravel zone on their base, have their shadow included and have the proper lighting.
They would have no function except blocking everything.
Four sets could be done for the different worlds.
For Greenland something like the Dolomites would be suitable (massive steep cracked),
Winterland should probably use the same set, only more snowcovered,
For the Desert, I can imagine slim towers of reddish rock (think of monument valley),
and finally for Blackland, which in my mind is a more surreal environment, I'd fancy black, broken, shiny hexagonal columns of basalt.
So far on the topic of mountains. I think they would be perfectly doable."
Animated volcanoes might also be handled similarly.