What is new in Age of Empires 2 HD?
The population limit has been increased to 500 (this is the only gameplay change).
The menus are looking better now.
The most important change and why the game is called “HD” is because the game will start in your monitor’s native resolution. There are two cheats to set the resolution to 1024 x 768 and 800 x 600. Check them here.
Playing the game in 1680 x 1050 or at even higher resolutions will not really work because everything from the map will look too small. There is no zoom-in option and you will barely see your peasants and units. In 1024 x 768, the game looks fine.
I’ve noticed that there is no delay when moving the map around, mostly because there are no patches like in the classic AOE 2.
These are pretty much all the changes. The graphic engine, how the maps/units/buildings are looking are the same as in the classic Age of Empires 2. Also, the missions from the campaign haven’t been modified.