* BreakthroughHit: This game solidified Creator/RetroStudios as Creator/{{Nintendo}}'s biggest western subsidiary.
* KillerApp: ''Prime'' was one of the reasons to own a UsefulNotes/NintendoGameCube.
* WhatCouldHaveBeen:
** There was originally going to be bits of voice acting included in the game. Files for names of each location exist, as well as an opening narration by Jennifer Hale. The PAL version of the game did include a new opening narration, but with a different voice actor.
** Kraid was going to be a boss in the Phazon Mines. [[http://images.wikia.com/metroid/images/b/b6/MP_Kraid.jpg He got far enough in development that he was modeled and textured]], but was cut for time. According to the modeller, Gene Kohler, he was not replaced by the Omega Pirate, who was already planned to appear before Kraid's cut. Concept art also showed a giant version of Mother Brain and different versions of Ridley (one showing his muscles and organs while another had him look more robotic), implying that those could have been in the game before the former got scrapped and the latter being redesigned.
** The Screw Attack and Speed Booster power-ups were going to be obtainable, but were scrapped. The Screw Attack was later added to ''VideoGame/MetroidPrime2Echoes'' while the Speed Booster wouldn't appear in a 3D ''Metroid'' game until ''VideoGame/MetroidOtherM''.
** ''VideoGame/SuperMetroid'' was planned to be included as a bonus. It was removed because it required a 3rd party emulator to work (Nintendo didn't have an in-house one for UsefulNotes/SuperNintendoEntertainmentSystem games at the time) and Nintendo didn't want to deal with any potential legal issues.
** The entire game was originally going to be in third person view, but Shigeru Miyamoto wasn't pleased with it (citing that it wasn't intuitive) and had the team scrap what they had so far in order to redo the game in first person view.
** It was originally intended for Samus to battle a much less restricted Parasite Queen; in other words, the Queen was not going to be fought within a container as seen in the final version of the game. This is shown in Metroid Prime 's [[https://www.youtube.com/watch?v=hwW8fpECZn8 very first trailer]], with the boss having much more freedom for movement such as running across the room and climbing on walls
** The Morph Ball almost didn't make it into the game due to the development team having trouble trying to make the transition from first person view to third person view being seamless as it was in ''VideoGame/SuperMetroid'' when Samus curls and uncurls in ball form. The dev team planned to scrap the power-up if they couldn't get the idea to work, but Miyamoto stated that if the team couldn't get the idea to work, then the game itself wouldn't work.