Is it possible to make a patch or something like that for the Map Editor, or perhaps an entirely new program, so that if we open an RMG template, we can open in Map Editor or something at least a general idea of what the maps generated from that template will look like?
Or is too difficult/not worth it?
The map editor uses the same rmg.txt as is used by the game, so you can just put the rmg.txt to data folder and generate a random map in editor.
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But to work gently It need a Launcher (a program which copies desired rmg file from set in directory to /data/rmg.txt and launches map editor, possibly even forcing it to generate random map on start, but the lattest could be done from GUI easily so the launcher is good even without it).