Unlockable: Phazon Mines in Single Mission mode.
Defeat the Omega Pirate in Multi Mission mode.
Unlockable Impact Crater
Clear each board destination in multi-misson mode.
Unlock Artifact Temple Stage For Single-Player
Just get to the Artifact Temple in Multi-Mission Mode. Once there, the stage should be rendered unlocked when your session is over. You will need twelve artifacts to reach the stage initially.
Unlockable: Phendrana Drifts in Single Mission mode.
Defeat Thardus in Multi Mission mode.
Unlockable Expert Difficulty
In multi mission mode, defeat the Metroid Prime on the Impact Crater map.
