Milk but he's a mask-wearing wolf (Thanks Wallhammer

Idea for my Subject 17 game, about halfway through, after you defeat a boss fight Subject 17, you are offered the choice to either shut down the Anomaly or let it continue. If you choose to let it continue, he decides to take the place of the previous 17, and the game ends. Your save file is deleted (you will get a disclaimer before making the choice), but when you reach that point in a new save, you will find that the Subject 17 will be the one from the previous save.