My favorite things about this series are the beautiful, yet creepy-looking environments, (I thought the vaults of Necrum were satisfyingly creepy and brought the tone of the game out very well for some reason.) realistic-looking movements of characters (the character animation in these games is amazing!
), the personalities of the characters-even the voice acting is top-knotch!
Also, I like the dark, yet goofy humor and the challenging gameplay that made me think of how to get out of a situation. All of these made the whole series fun.