A free mod for Fallout 4, by 5133p39.
Sneaky Killmoves is a mod which will allow you to perform stealth attacks by sneaking up on your enemies and backstabbing them. It is a very powerful attack, which can kill any mob, even if they are using some kind of guard animation. The best thing is that you can use it even if you are not in the same position as your target, as long as you are able to sneak up on them.
It is very easy to install, as it is a zip file. You just need to download it, open it, and install it. It is not a mod, it is a standalone application. You will not need to download any other files. The instructions are very easy to follow.
