Catechesis is a horror-themed role-playing game set in a dark, immersive world where players assume the role of Daniel, a demon-possessed altar boy. The game features a compelling narrative intertwined with anime-style cutscenes, allowing players to engage with unique characters while navigating a rich storyline. Players must balance their virtuous day life with battling demons at night, creating a dynamic gameplay experience. The game also incorporates stealth mechanics, enhancing the tension and excitement as players navigate their environment.

In addition to its gripping narrative, Catechesis offers a detailed day and night cycle, where players attend school and work by day, preparing for nocturnal adventures in dungeons. Combat is thoughtfully designed with a twin-stick aiming system, allowing for strategic engagement using both ranged and melee weapons. Players can explore the environment using a flashlight or candles to uncover hidden resources and lore, all set against a captivating soundtrack by Michael Kelly, enhancing the overall atmosphere of the game.