This was made by Ash Law with the brush over on G+:
(reposted with his permission)
RuinedTown.png

He posted it with the following comment:
+Jesse Morgan 's GIMP brush in action! 5 minutes to get a ruined/abandoned settlement.
After some prodding from some other guys on G+, I've added the brush as a "pay what you want" on Drivethrurpg. If they do well, I'll make more.