Tiberiumkyle

From what Ray has talked about on the discord server, the game pre-renders the entire map (a 4k texture) then only edits the changes, while you're playing. So you'd need to rewrite the map rendering engine.

Looks like the courier AI is having some problems. Ray will likely want to poke at the save, you can upload it from in game, the profile selection page, arrow next to the profile. The game will say if it worked or not.

After uploading it for Ray, it might be fixable by selecting the region on the world map, holding shift, and clicking the 'reset ai' button.

Your plan will require some careful testing to see if it's actually doable at all, since monsters get very unhappy if you try to completely wall yourself in and leave them no routes. You'll still need a 'weak spot' that's significantly weaker than the rest of the walls to make them go there, instead of whichever section of wall they decide would be quickest to tear down to get at you.

Did the game crash, or did you close out of it normally?

If crashed, it likely opened up the crashlog in notepad or whatever your default text editor is, and steam thinks that's the game itself, cause the game launched it.

If not, steam wonkiness

A save rollback is the only way to save the village, unless you've already pushed the backup saves past the point the bug occurred in the first place.