An old rusty key found deep in a cave, what could it open? Explore a dense world, fight ferocious enemies, and solve puzzles in search of answers. Master key features: Item based exploration Dozens of enemies Shops, weapons, and powerups Dungeons Between 5 and 20 hours of content Lots of secrets No language support! The game doesn't hold you by the hand, it's a love letter to hiking and exploration. You have to find your own path and nothing is story-gated.