Normally I don't read a lot of books but now I really want to give it a try and read something that will be enjoyable. I would love to find a book that resembles Skyrim in its core. Something dark, mysterious, having grownup characters with complex personalities, (I dont quite like when the protogonist is the typical teenage boy or girl).. Also I would love to be good descriptive book, the environment described in full, the setting our chapter is placed in. etc etc...

I know its a big shot but I really hope I will find a book that looks something like my description!

And I hope I will get help from you guys!

Not really in the category you're asking for, but you should read It by Stephen King.

The Darktower Series by Stephen King.... has everything you describe

The Obsidian Mountain Trilogy by Mercedes Lackey. Dark fantasy, dragons, several races....

http://www.mercedeslackey.com/books/mountain.html

"Skyrim in it's core"

• Conan the Barbarian by Robert E. Howard

Sword and sorcery, a bit of intrigue.

• Dune by Frank Herbert

Sci-fi style with lots of lore, political intrigue, and great characters you'll remember and quote for the rest of your life. The series will keep you busy for some time (you may even consider picking up the series continued by Herbert's Son.)

Conan, the original storied by Robert E. Howard.
Dune is also kind of like that.

Thank you guys A LOT for the ideas, I am searching every recommendation now on goodreads just to read the description and pick my book!

Dragonlance series. Dragons of Autumn Twilight is a good place to start.

The one I linked above includes a couple chapters if you want to check them out.

Homicide: A Year on the Killing Streets by David Simon.

Stalingrad, D-day and Berlin by Antony Beevor are cracking reads. Opened my eyes a lot to what happened in WW2.