The forum searching I've done hasn't really revealed anything about movement physics. My hope would be to see realistic movement in the game, instead of the usual arcade-style movement that most games of this nature generally use. Specifically, I'd love the player's body to feel like it actually has weight/is affected by gravity/inertia while moving.
• if you are running in one direction, changing direction sharply should "feel" more difficult
• traversing obstacles should be realistically cumbersome & interfere with the ability to attack
• changing from a prone style of shooting to a standing position (or vice versa) should not be instantaneous
• falling from sufficient height should cause the player entity to stumble & not just cause fall damage
• getting hit with ancient weaponry/melee attacks/explosions should cause the player entity to stumble
• swinging heavy weapons should affect the speed of the attack relative to the weight of the weapon
... etc. You get the idea.
I've worked a fair bit with the Unreal 4 Engine before (I absolutely love the node-based visual scripting), so I know these types of physical effects aren't incredibly difficult to employ... but creating this level of realism is definitely time-consuming! Especially if the game has already been built from the start with more arcade-y style gameplay, I can certainly understand if this never makes it into the game.
This is just a style of gameplay that I personally prefer... ┐(￣ー￣)┌