How much of this game would you want to be focused on the hyper realism of human vs. human theme and how much would you like to see the combat and story inclusion of the supernatural elements?
Personally, I would like it to be grounded in reality for about 99% of the game until after you beat the last encounter which concluded with your Ellen Page looking companion disappearing only for you to find her dead with a gaping wound on her neck. Your main character, loosing the last thing he had in his life, pulls a gun to his head. All of a sudden, your companion begins to twitch. Your character looks down at her. She opens her eyes, snarls her teeth which are now razor sharp and jumps at you. Your character now aims the gun at her and pulls the trigger. Credits roll. Werewolf Zombies. Calling it.