You encounter Book Simon in the final nightmare sequence after Simon finds the book in his room in Kirkville. Upon finding the book, a flashback-like cutscene occurs, much like the start of the other three endings. However, S Simon does not shoot himself, instead, the door opens and Book Simon is shown. You then play as S Simon, traversing through the final nightmare sequence, Psychosis, with limited movement and only one gun. You can move a bit faster if you tap W multiple times at the right time. You have to fight B Simon four times, as he flees any time you deal enough damage. First, he is armed with a glock. Next hes armed with a MP9. After that, hes armed with a shotgun.  Lastly, during the final part of the battle, he arms himself with a flare and a sledgehammer, doing high damage. Of course, if you die during this battle, there are two saves in Kirkville, one in the kitchen, and another near the stone fence when you exit the sewers.