[Wishlist] What do you want to see in the next Age of empires II expansion (if there is one)?

People are always demanding for new civs, but I really would want to see some clever tweaks in respect of terrains and gameplay.

1. Hills should grant more visibility, just to make them a bit more strategically important and contested.

2. Wall should allow garrison. The addition of seige Tower only further highlights how ridiculous wall in AOE2 is. Do all those units jump from atop the seige tower to land on the other side of the wall. Archers behind the wall shooting arrows that penetrate the wall? That's a joke. Walls should become a buildable terrain which units can walk on. So it will be like a cliff but with hp. Seige Tower then unloads the units to the cliff-like wall.

3. Different units fight better in different Terrain. Infantry should fight in dense vegetation (bushes). Cavalry in open field. Archers behind cliffs and atop hills. This should further open up new and exciting style of gameplay.

These are some of my wild thoughts. What are yours?