The player controls indentured servant girls Helen, Betty, Dorothy, and Margaret as they do their assigned chores in an empty mansion, following false promises of their freedom. However, three of the girls are gradually picked off by an unseen monster, leaving only Margaret remaining to escape.
As written in the game's notes, the girls are test subjects of Dr. Edward Sullivan, the owner of the estate and a veteran in World War I. Upon his return from the war, Sullivan begins to experience a PTSD-induced fever-like "heat" that gives him visions of an eldritch god. This "heat" spreads across the world like a virus and brings forth a cult of fanatics dedicated to the resurrection of this god. With their support, Sullivan surgically resurrects the dead in a failed attempt to provide the god an avatar to possess, littering the mansion's underground laboratory with undead monsters
Margaret fights her way through Sullivan's ungodly creations with a rifle and escapes the mansion's grounds.
- The game is an homage to Italian zombie horror movies.
- The gameplay mechanics were inspired by the early Resident Evil and Silent Hill games.
- The soundtrack was composed by MXXN.
- The story of The Glass Staircase is similar to Amnesia: A Machine for Pigs (2013), and Alone in the Dark (1992).