Seasons!

How about seasons in the game for a nice change\wrench in the works for things? Wheat would grow best in the spring and fall and have the maximum output. Winter and summer slower. Flour would have maximum output during the windy seasons. Beer production during the warm seasons. Maybe hardwood grows faster in the winter and pinewood in the summer. Tools, smelters when it's cool (it's hot working by the fire!) etc, etc whichever you devs find to be the most authentic.

It would be an interesting addition to production.