The G.F.S. Valhalla was an Olympus-Class battleship that was attacked by Space Pirates during a training mission at the Klar Nebula in the Gaflar System. The Pirates had devastated the ship, slaughtered her crew and stole the ship's Aurora Unit, designated Unit 313. After collecting their prize, the Valhalla was abandoned and left adrift in the nebula.
Though the ship had suffered severe damage, and many of its areas are even exposed to the cold void of space, most of its systems still operated in some sections. However, most of the facilities were underpowered and could not be operated. By plugging Energy Cells into power sockets, these facilities could be reactivated and allow access to other parts of the Valhalla.
The ship is overrun with Phazon-based or Phazon-mutated creatures, such as Phazon Metroids and Phaz-Ing, and many rooms are infested with Phazon growths. These creatures were most likely used by the Space Pirates during the attack. Because of them, exploring the Valhalla is extremely dangerous.