My Boyfriend Butz posted about my town earlier in this thread, I've killed many perfect fruit trees all over my town and just left them. It really gives the town a very haunted forest feel.
Some other ways I make my town look like its creepy and haunted: Eerie streetlights, weeds everywhere, trash from the river everywhere (think tires), a creepy town tune, Random dirt patches everywhere (I run everywhere purposely), mushrooms everywhere, and some other stuff I'm sure I'm forgetting right now, I'll post later if i remember anything else!
Also: Many PWP's can be scary and creepy if you put them in the right place, for example: The water-well slightly off a worn dirt path surrounded by Mushrooms, as if it were under some dark enchantment. The stone Windmill or the lighthouse on a cliff deep in the haunted forest as if they were cursed. Or the bus station, totally grown up in weeds and dead trees in a secluded part of town that seems like it shouldn't have a bus station, as if it services ghost buses in the middle of the night.
The biggest thing (I think) with making Post Apocalyptic/creepy/haunted/deserted towns etc. is using your imagination, and pretend like your trying to build a movie set. Think about all the different ways there are to set the mood and suggest the past and you're good to go.
And then have fun with the challenge of making something
dark and sinister with the tools this wonderfully
light and happy game has given us!
Hope it turns out well! And I hope we all get to see it someday