nicely done, but trees are spreading way too quickly, making this an incredible resource hog. after a little map generation by venturing just a little around my starting area, my game became horribly laggy, unplayable basically (i'm using an i5 4690K @4GHz, so no potato here).
maybe you could reduce the expansion of trees and put a hard limit to the number of trees on the map? until then i'd call this gamebreaking...
