Planet One is a location in Fable III that is accessed through the MourningwoodDemon Door. To open the door, players must upgrade their melee or ranged skill to level 5, by opening the final melee or ranged chest on the Road to Rule, and then draw a melee or ranged weapon when prompted by the door. Contrary to popular belief, the weapon does not have to be a fully upgraded legendary weapon. It can even be a hero weapon.
Planet One is a desolate unknown planet with geography similar to the moon. There is another moon orbiting it. There is a chest that contains the full Military Suit. Along with the chest there is an orrery that allows the player to change the environment and local celestial bodies. There are 6 variations.