Gregory Horror Show: Lost Qualia is a Gacha-based RPG mobile game that combines the elements of dungeon crawling with a Gacha card system. Lost Qualia uses the original 3D cube-esque graphics and style that the series is known for. The Gameplay combines the elements of roguelike dungeon crawling with a Gacha card system and has the Player, Gregory, and various other playable characters navigating a randomized labyrinth, where they have to fight through hostile enemies which lurk within the dungeon. The player can use a variety of attacks, items, or Gacha cards to help them defeat enemies and complete the game's various levels. The primary objective is for the player to survive and reach the goal to complete the level.
The main story revolves around the player (chosen between two genders) arriving at Gregory House, where Gregory, the hotel's manager, meets the player and tells him about a previous guest known only as "that man". Gregory further explains that the previous guest's delusional beliefs and paranoia have enabled him to grow too powerful, and take over the hotel, turning it into a series of randomized dungeons. Gregory enlists the player to help him, and various other hotel guests, take back Gregory House and defeat "that man."