Nightmare's Room connects to a Navigation Booth, which Samus Aran should use due to the unexpected battle she fights here. She enters this room on the way to Sector Zero, and the camera automatically pans to a Door at the top of the room.
The room is shaped cylindrically, and features four long platforms that circle the room. To access each of these, Samus must use the three Kick Climb shafts that are placed in the room for her convenience. The platforms sometimes have gaps in them, and Grapple Points over said gaps, although the Space Jump can be used as well. The long and round nature of the platforms also allows for Shinesparking across the room. The room appears to have been slightly frozen over.
At the top of the room, several cables power up a machine whose "tail" is visible. Just as Samus is about to exit the room, these cables supercharge the machine, and reveal the Nightmare, who manipulates the gravity to hinder Samus' actions, and then engages her. Samus fights a long and frustrating battle with the Nightmare, before its faceplate cracks, revealing its true face, and it slams into the walls and platforms in its death, before falling to the ground dead.
Samus, believing the monster to be dead, enters Sector Zero only for Adam to destroy it and himself. While returning to the Bioweapon Research Center to secure the safety of a survivor, Samus again passes through this room. Again, right when she thinks she can leave the room, the Nightmare re-awakens for another battle with Samus. Since she activated her Gravity Feature while escaping Sector Zero, she is no longer hindered by the manipulated gravity, although Nightmare employs a frustrating black hole attack in response. Despite this, Samus is able to best Nightmare once again, and this time it explodes into several pieces, while its face darkens and decays. It remains here until the Galactic Federation's intervention, and is later seen on the Biologic Space Laboratories research station.
- There is a machine at the bottom of the room that very much resembles the Gravity Suit powerup in Super Metroid. This may refer to the Gravity Suit being the reward for defeating Nightmare in Metroid Fusion, or a reference to its gravity manipulating capabilities.
- Concept art of the room states that it was discovered by ex-Federation Army soldiers, and that the room's Kick Climb shafts are used for cargo transport.