I'm sooo happy you loved the game and the world building, there is so much I want to tell about their world that isn't in the game!
It's actually the hardest one to get, you actually have to be well liked by Styx, but not enough for you to get the happy ending, you must have 7 or 8 love point with Styx, but I'll have to push a new update tonight so I will lower the difficulty !