Ending 20, termed "Remaining Ending" ahead of The Binding of Isaac: Repentance, is unlocked right after defeating the boss Delirium, that's Isaac's representation with the "light-weight at the end of the tunnel".[16] It builds upon events seen in Endings 12, fifteen, and 17, and shows Isaac recalling his Recollections in https://binding-of-isaac-liberty00963.bloggip.com/28556583/the-fact-about-isaac-liberty-cap-that-no-one-is-suggesting