Image Gallery #1:
Scan 50% of the creatures & research data.

Image Gallery #2:
Scan 100% of the creatures & research data.

Image Gallery #3:
Beat the game under Hard difficulty.

Image Gallery #4:
Collect 100% of the power-ups.

Three different endings:
Beat the game with under 75% completion for the standard ending. Beat the game with between 75% and 99% completion for the better ending. Beat the game with a 100% completion and you'll get the best ending.

NES Metroid and Metroid Fusion Suit:
You will need a copy of Metroid Fusion for the Game Boy Advance. Beat Fusion, connect your Game Boy Advance with a link cable and you will be able to play the classic NES Metroid on your GameCube. Beat Prime, connect your Game Boy Advance with a link cable and you will be able to play Metroid Prime wearing the Metroid Fusion suit.

Thanks to Revolution readers Jay Psychotic, Odie, Leland Taylor, Nick Cal and Willy Wonka!