Improved/Diversified Sound Design
Add different sounds for the different types of trees/vegetaion. Also, when clicking on a dead tree or a tree stump, you can still hear the sound of the leaves, even though, they´re not there anymore.
Maybe also sounds that are appropraite for the size of the building e,g, have the sound of a large water tank have more low end and/or reverb, than a small one. Also different sounds depending on how much of the tank is filled.