I'm making this thread to give people a place to, well, list off simple improvements or alterations that could just be patched into the game, things that don't require an entire new game to be brought into existence. Atm I can't think of any but that doesn't mean that this thread won't gain some use.

Make dead bodies have collision. I want to throw dead people at live people!

Nightmare difficulty, please.

New Game +

That is all.

I agree with harley

Enemy AI detects opening doors in front of them (they do notice if you take something that's in front of them, so why not doors?);
Enemy AI knows which doors should be closed / are off limits, and react to those doors not being what they should be if there are none of their buddies (other enemies) around;
Enemy AI, when not alert, notice and remember the status of doors (open/closed) and become alert (look around);
Enemy AI search patterns extend more often to adjacent rooms;
Enemy AI looks hard for buddies that are not where they should be, alerting others to the missing ally (as is, they notice it, say something, most often do nothing and just keep walking);
Tweaking of the Blink-Targeting (for consoles/gamepad) - more accuracy in tight spaces;

if they were to add that it would have a major impact on performance, which is likely why its not there in the 1st place

More ways to take out enemies , nonlethally.And nonlethal gadgets like smoke grenades,a device that makes noises for distracting enemies it would be used in a similar way as a spring razor trap.