Dark Souls is an RPG modded adventure minecraft map based on the same title game made for PS4, PC and XBox.
So the real Dark Souls game is supposedly hard and dying hundred or thousand times is normal in the game. One hit K.O is not unheard of.
This map basically recreates those environment in Minecraft
To play this map you require lordran modpack. Lordran modpack is only for minecraft 1.12.2 so you need to be on that version to play this map.
Another thing needed is skin pack which you can download here