Cool concept. Do resources flow into some kind of "town" or "market" in the end? If not, how are the end products used? Are resources like forests "replenishable", or can forest not grow back after being harvested? Think some optimization puzzles would be nice to implement, example: Goal: Produce 10 goal/minute with < 10 buildings, Limitation: 30 minutes. Different puzzles would have different goals and limitations.
Keep it up!