When people say that the plot here is dark that can mean one of two things:
1. The world is dark, the protagonist does some evil shit and sees some evil shit but he "wins" in the end and gets a happy ending even if it's "happy" only from a player perspective. Makes you ask hard questions and thing about life but does not make you feel drained or defeated at the end.
2. The world is dark, the protagonist does some evil shit and sees some evil shit and gets a sad ending. Loved ones die, romances don't pan out, and the player overall feels like he got punched in the gut in the end.
Which of the two sorts is this game?