Million Depth is self-described as "deep-diving action strategy game". The player controls Moma, who has access to a crafting system where they can create the character's own weapons and other tools from materials found in outer space. Each creation has different properties depending on how the player combine resources. In battle, time advances only when the player character takes action.[1] The game has 1 million floors to explore.[2] Moma's oxygen meter depletes as the player goes deeper, and has to be recuperated to continue.[3] It has multiple endings depending on the player's progress.[4]