The Oubliette is an Alimbic space station created to contain the creature Gorea. After containing Gorea in the Seal Sphere, the Alimbics used the Alimbic Cannon to send it into the Infinity Void. Samus later uses the cannon to bring it out again. After Gorea is defeated, the Oubliette explodes.
The first areas are relatively straight forward, consisting of an elevator, a teleporter, and a straight path. One room is surrounded by windows with unknown colored symbols. This room also has a number of Alimbic Datashades in it. It another room, there is a morph ball tunnel on the right as Samus enters the room. This tunnel follows a number of roots to a suspended teleporter which leads to an Energy Tank.
The Main Chamber
The main chamber has a large central island that once held the Seal Sphere before its destruction. This island is surrounded by a pool of a damaging substance, with a rim of safe ground. Along this rim, Trocras spawn. There are also 6 devices along the walls that can be activated by the Affinity Weapon that matches their color in a specific sequence indicated by Alimbic Prophecies. If the devices are activated, the true final chamber can be accessed.
The Final Chamber
The Final Chamber is only accessible when the devices on the walls of the main chamber are activated, and will be bypassed if a player does not activate them. This room is essentially filler with a platform supported by a large twisting structure. The Omega Cannon can be found at the bottom of this room, and is required to beat Gorea's final form. The structure can be climbed with the aid of Jump Pads.
There is a multiplayer stage of the Oubliette that is essentially an exact copy of the Final Chamber. The only changes are that the Omega Cannon is now at the top, and players spawn at the bottom. There are also a few more energy units throughout the room.
The top level of the final chamber, with the Omega Cannon