Adjustable and zoomable camera. The character seems far away in high resolutions. Lowering the camera in Div2 limits your field of vision and bounces on the terrain.
The ability to swim under water.
The ability to bind x+x hotkeys (eg. CTRL+A, SHIFT+1, etc.)
Loot drops by non-boss enemies. Even if it's just a few coins or a reagent.
Non-stupid looking weapon models and textures. I've yet to find a melee weapon that doesn't look like Dr. Seuss threw up on it.
Set items put into their own random loot table instead of every piece showing up in exactly the same place. Limits replay and diminishes the satisfaction of getting one.
