Be warned: this game is totally nerd overrated and very old school in a bad context.
I paid 1 EUR in a sale and this was 1 EUR too much. Even skip it if it is for free. Yes, the atmosphere of the game is amazing, but that's it.
Playing until the second cathedral mission was pure horror, very hard work and no game fun to me. Most missions are endless due to huge maps and a bad orientation system. There is a map function in the game which is really bad implemented. Sometimes the map consists of various paintings which is totally misleading. In the beginning of the level the starting position wasn't shown. One time I wandered around for more than one hour to find the exit, which was the last mission task!
In some levels I had to watch several youtube vids to understand what to do next and where to go. I couldn't finish the first cathedral mission due to a game breaking bug. I had to use a cheat to end the mission to be able to go on. A door didn't open. I wished I had stopped playing.
In the second cathedral mission you will be hunted and surrounded by zombies, ghosts and dead guards, which must be heaven for sadomasochists. One dead monk gives you confusing additional tasks. I had to reload again and again and again due to permadeath after each few seconds. Ridiculous was that sometimes the guards won't see me in the shadows and sometimes they know exactly where I was. Sometimes I was killed by zombies through a closed door. And hooray there was a mission with a time limit. You have to deactivate 5 levers in 5 minutes in a huge building to open a door. The levers were shared in several floors and in the garden. What an ingenious idea?
Do yourself a favor and play a good game instead of this one.