Oneiro is a single-player action, adventure, RPG, strategy, simulation, survival, dungeon crawler, roguelike, and sandbox game in which players explore a procedurally generated mental labyrinth, utilizing skill, creativity, and knowledge to progress through its depths. In this game, players navigate a surreal, psychologically themed environment where they collect and stack items, gears, and weapons to combat manifestations of their fears, facing perma-death and challenging scenarios that test their resilience and strategic thinking. It stands out with its combination of advanced gameplay elements such as procedural generation, first-person perspective, and physics-based sandbox mechanics, offering a deeply immersive experience that emphasizes player skill, creativity, and mental resilience.