Or maybe a tool to mark areas which you can hide in? That way you can have all types of hiding places - lockers, bushes, tall grass, etc.

No, you can hide in any dark area and you are almost invisible. You can also hide behind props.

So basically all enemies are blind thats a bit stupid considering In real life ( I know this is a game) If someone was sitting in a corner of a dark space they could barely see you but go and investigate at least add a real life perspective to it If i stood in a dark corner next to a combine soldier stood up they wouldnt see me at all, Much logic many sense

They move to investigate if you are at a certain distance, but they barely do that if you're in a completely dark area. I'll try to change that, adding a fixed minimum investigation range.

But it still is kind of nonsensical and silly that you can't hide behind or in a patch of tall grass because the mod doesn't work with effect props.

The mod works with what I tell it to work with, I can't please everybody. Also, I can't think of a map with tall grass. If there's any, they are probably very few. An entity for hiding inside like a locker or a barrel would be interesting, but I'm not playing much GMod lately. Honestly, I only play it to add a few missing features I didn't implement in the last update, but I'm going to leave it one of these days.

Ok Max sorry I know your new to Lua i shouldn't expect you to be able to do everything from the start.

Well, I found the alien NPC mod (From Wheatley) that has lockers, I use it for stealth often. (And it works) Link: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=532921450

I know that addon. It's not that I don't implement something because I don't know how. Most of the time I don't do it because I'm lazy, or because I just don't want to. I told you, I'm not playing much GMod lately. I just want to add a few missing things and take a break from it.

Yeessssss!!!

there a prone mod but there is a problem, npcs hear louder foot steps when in prone.

plus sorry for the bad english

I would have to add compability manually for it to work properly.