History VideoGame / MetroidFusion

''Metroid Fusion'' is an action-adventure platformer video game published by Creator/{{Nintendo}} for the UsefulNotes/GameBoyAdvance. It was released in North America, Europe, and Australia in November 2002, and in Japan in February 2003. The game is considered to be the fourth main installment in the ''Franchise/{{Metroid}}'' series; the intro alternatively refers to the game as ''Metroid 4''. ''Metroid Fusion'' was developed by the same development team that created the previous ''VideoGame/SuperMetroid,'' to which ''Metroid Fusion'' bears heavy resemblance.

The game got re-released on both the UsefulNotes/Nintendo3DS (as a part of the console's Ambassador's Program in 2011) and the UsefulNotes/WiiU's Virtual Console lineup in 2014.

[[SequelGap Nearly two decades]] of DevelopmentHell later, the long awaited follow up, ''VideoGame/MetroidDread'', was announced for UsefulNotes/NintendoSwitch. A few years after ''Dread'''s release, ''Fusion'' would be added as part of the Nintendo Switch Online Expansion Pack service in March 2023.

* ConsoleCameo: The UsefulNotes/NintendoGameCube makes a small appearance as [[https://cdn.discordapp.com/attachments/369213387873452033/823414448492380170/unknown.png part of the junk blocking the air filters in Sector 1.]]

* DarkerAndEdgier: Than the previous games. ''VideoGame/SuperMetroid'' was darker than the previous series, but this game is almost a SurvivalHorror game in tone. Samus has to run for her life should she encounter the SA-X, who possesses her upgrades and Ice Beam. Not to mention the Nightmare is one of the most horrifying bosses in a UsefulNotes/GameBoyAdvance game. [[spoiler:Even the formerly benevolently portrayed Federation is shown to have shady goals that force Samus to turn on them, which she realizes will make her viewed as an enemy.]]

** After getting the Varia Suit back, the formerly harmful blue X become harmless like all the other types, but the X (who intentionally suicide bombed you to weaken you) don't know that yet, so rather than immediately starting to run away, the first few blue X you find will continue to suicide bomb you, only running once they see it's stopped working. You can even keep on purposely avoiding the Blue X to prolong the time it takes for them to stop the kamikaze attacks.

* PermanentlyMissableContent: There's a power bomb hidden in the research laboratory [[spoiler:obtainable only during the detonation sequence.]] Should you miss it in your panic, there's no way to go back and get it [[spoiler:as the section it's in gets ejected to [=SR388=].]]

* PointOfNoReturn: Once you [[spoiler:go up to the main deck to alter the station's trajectory]], every possible route back to the various sectors is sealed off. Your only option left is to finish the game. Except in the EndgamePlus, which does not seal off the sectors until the final evacuation countdown.

* SurpriseCreepy: Metroid games are not unknown for having a dark, desolate atmosphere, and ''Fusion'' is no exception. What ''is'' unconventional for the series is the extent to which the game incorporates SurvivalHorror elements. Samus's SA-X clone will pursue her relentlessly, and until much later in the game, there is no hope of fighting it - the only available choices are to run and hide.

* ClimaxBoss: Nightmare. It has been foreshadowed throughout the game, even making appearances in the background of Sector 5 at the end of the first visit, and then it causes the most destruction to the station firsthand, including destroying most of the cooling units of Sector 5 and breaching a water containment unit from Sector 4. It is also arguably the most difficult boss in the entire ''series'' much less the game, and its defeat grants you enough defensive ability to reliably take on the rest of the game. As far as its impact on the subsequent narrative goes, [[spoiler:you must take a detour through Sector 4 that leads to you unlocking the Level 4 security doors and downloading the Diffusion Missiles, both of which get you chastised by Adam for not following procedure and providing Samus the first major hint that she is being lied to.]]

[[SequelGap Nearly two decades]] of DevelopmentHell later, the long awaited follow up, ''VideoGame/MetroidDread'', was announced for UsefulNotes/NintendoSwitch.

* SurprisinglyRealisticOutcome
** One case that makes up pretty much the entire point of the game is that the X Parasites have emerged because those super-dangerous Metroids Samus spent the previous two games eradicating [[NiceJobBreakingItHero were keeping those parasites in check]] - turns out you can't just remove a species from its food chain entirely and expect what's left to sort itself out without far-reaching repercussions.
** Much of Samus's Power Suit had to be surgically removed (since it couldn't be taken off while she was unconscious from the X infestation) before she was given the Metroid vaccine, and as such her new Fusion Suit is a ''massive'' downgrade in protection, missing most of the explicit armor plating the old suit had. This is [[GameplayAndStoryIntegration reflected in gameplay as well]], as Samus in this game takes by far the most damage in the series. One upside, though, as demonstrated by contrast with the later ''VideoGame/MetroidZeroMission'', is that the Fusion Suit is also much lighter, as she can cling to and lift herself over ledges as an inherent ability, rather than requiring a powerup.

* DubPersonalityChange: Applied to an entire government entity rather than a character in this case. The Galactic Federation in the original Japanese is presented as a complex network of independent branches, while it's addressed as a singular entity in the English localization. [[spoiler:This has the side effect of making the entire governing body appear villainous in the English release, as the hidden project to clone and weaponize Metroids and X are attributed to the entire Federation rather than a single potentially rogue branch like it was in the original Japanese.]] This discrepancy would unfortunately carry over into ''VideoGame/MetroidOtherM'' with even more contentious results.

Now sporting much altered armor, Samus is sent to the B.S.L. space station to investigate an explosion. There, she learns that the station is swarming with organisms infected by more of the gelatinous lifeforms -- now given the name X Parasites -- organisms that can infect a host body and take control of its central nervous system, allowing the X to control the host body. The X Parasites are then able to become an exact copy of that host, complete with the memories of the infectee. The fact that Samus now has Metroid DNA within her allows her to absorb other X Parasites. This is because the Metroids, genetically engineered creations of the [[{{Precursors}} Chozo,]] were made to be predators of the X; the recent Metroid purge let them infect the creatures on [=SR388=] and spread once more. In order to check the spread of the infestation, Samus must work her way through the station under the guidance of her new gunship's Artificial Intelligence and eradicate the X Parasites and their host bodies.... But among them is the SA-X, a clone produced from the remains of her Power Suit, with all of her weapons and powers at its disposal.

* BackgroundMusicOverride: After [[spoiler:Adam orders Samus to propel the B.S.L. station into [=SR388=]]], the song [[https://www.youtube.com/watch?v=aRYO-qnX24o "Last Instructions"]] plays everywhere until Samus [[spoiler:starts the propulsion sequence]], when it's replaced by [[https://www.youtube.com/watch?v=lsYyzqc_5vg "Station Escape Timer Mission."]]

* BeingGoodSucks: At the end of the game, Samus [[spoiler:sets the B.S.L. on a course to crash into [=SR388=] in order to kill all of the X Parasites in both locations, going against the wishes of the Federation members who wished to study the SA-X]]. She fully expects the public to hold her accountable and launch investigations for doing this due to not knowing the full reasoning behind her actions, but Samus fully believes that she made the right choice.

* BittersweetEnding: Samus saves the galaxy again [[spoiler:and reunites with former allies (even one previously dead). But in the process, she permanently destroys the B.S.L. space station and [=SR388=], and was forced to defy orders to do so. Samus got new friends, but is now likely to face scrutiny for seemingly committing an act of terrorism against the Federation. However, the Japanese script shows that the Federation isn't politically monolothic and is made up of multiple of branches (something that was LostInTranslation in the English localization), and the beginning of ''VideoGame/MetroidDread'' shows that she's still on good terms with the Federation. So, if someone within the conspiracy party tried to brand Samus a terrorist, it was an accusation that didn't hold in court.]]

** The general color of the cold-themed Sector 5, ARC, is blue. The lights for its elevator are a bright cyan, the B.S.L. tiling in the non-cold rooms are various shades of pale blue, and the cold rooms are vibrantly cyan and blue.

** Despite being a lone-wolf bounty hunter, Samus clearly still cares about maintaining stability in the galactic civilization. However, she recognizes that the Federation is WAY out of their league [[spoiler:when they decide to capture the X, especially the SA-X, for their military applications. However, the only way for Samus to solve the issue and prevent the X from leaving is to crash the B.S.L. station into [=SR388=] and destroy the X that way. However, in doing so, her action is basically interpreted as an attack on the Federation and thus the galaxy at large, the very thing she's constantly fighting against. However, Adam reassures her that somewhere, someday, someone will understand.]]

* CliffhangerWall: ''Fusion'' spent 19 years as the final game in the series' timeline, ending with [[spoiler:Samus causing the destruction of the B.S.L. station and the planet SR-388 in order to stop both the Federation's secret cloning research on Metroids, and the spread of the deadly X Parasites]], leaving her future relationship with the Federation unknown beyond an in-universe acknowledgement that she will most likely have to face trial for her actions. During the intervening years between it and the release of ''[[VideoGame/MetroidDread Dread]]'', the franchise saw six games in the ''[[VideoGame/MetroidPrimeTrilogy Metroid Prime]]'' sub-series (including a pinball game) and [[VideoGame/MetroidZeroMission two]] [[VideoGame/MetroidSamusReturns remakes]].

* ColonyDrop: B.S.L., at the end, [[spoiler:ends up with its orbit altered to intercept [=SR388=]. It crashes down on the planet with its self-destruct activated, destroying both it AND the planet.]]

** Various locations on the B.S.L. station, such as the Central Reactor Core and the Boiler Room, will be in full operation if visited before their respective crises occur, via sequence breaking. An exception to this is the area outside Nightmare's boss room, which is already ransacked even before his rampage.

* EarthShatteringKaboom: [=SR388=], [[spoiler:when you [[ColonyDrop collide the B.S.L. station]] with the planet. The station's self-destruct had been activated and its orbit had been altered to intercept the planet. The explosion is powerful enough to completely destroy the planet.]]

** At the end of the briefing on Serris in Sector 4, the AI notes that they can't cut the power to the B.S.L. without causing problems on the station. [[spoiler:Nettori's roots end up doing just that after you collect the Power Bombs.]]

** Also, the Federation had preserved a Metroid cell culture from the Metroid Hatchling. A vaccine made from these Metroid cells was used to cure Samus when she was infected by an X in the game's intro. [[spoiler:And they also used it to grow new Metroids in a restricted laboratory hidden on the B.S.L. Station. Adam claims that this was only for "peaceful applications." This follows from the events of ''Other M,'' where the Federation was also breeding Metroids.]]

* GrayingMorality: This game paints the Galactic Federation as becoming as [[TheUnfettered Unfettered]] as the Space Pirates (though [[LostInTranslation in the Japanese version]], it's said to only be a subset of the group). Over the course of the game it's revealed [[spoiler:they have been weaponizing Metroids (for "peaceful applications," though Samus doesn't buy it since she knows how uncontrollable they can be) and that, based on the events on the B.S.L., the X Parasites (and SA-X specimen specifically) could also be potentially weaponized (which, again, sends Samus sideways that they would think that trying to cultivate such things wouldn't be a disaster waiting to happen. Not helped by the revelation that they were ''deliberately'' withholding upgrades from her so she couldn't kill the SA-X). She destroys their research in order to prevent any of this from coming to pass, but expects that she will be branded a traitor -- though Adam insists that at least one of them will understand.]]

* HeroicSacrifice: Samus almost attempts one [[spoiler:by detonating the self-destruct charges on B.S.L. to destroy the X Parasites aboard; herself included. The AI Adam, however, informs her that doing that would be stupid, as it would not destroy the X on Planet [=SR388=], and only serve to destroy the X's greatest obstacle: Samus. A different plan is then created, which destroys all the X in both locations and allows Samus time enough to escape the station.]]

* ItsTheOnlyWayToBeSure: [[spoiler:Adam persuades Samus that simply activating the self-destruct system on the B.S.L. station isn't enough, and ''it's what the X want'', because it spares their brethren on the planet below. Instead, the AI implements a plan to change the orbit of the moon into a collision course with [=SR388=]. The blast would eradicate the X (indeed the impact and detonation destroys the planet).]]
* KaizoTrap: In the game's finale, [[https://www.youtube.com/watch?v=KoSf5ahQooQ it is possible]] to defeat [[spoiler:the Omega Metroid]], then have the timer run out while [[spoiler:Samus's Gunship is docking.]]
* KillAndReplace: The X mainly infect lifeforms to absorb their DNA and memories while killing their host, which they can then perfectly replicate. This notably happened to the crew of the B.S.L. station and many other creatures, to the point that all (save B.O.X. and [[spoiler:the Omega Metroid]]) of the enemies Samus faces in-game are mimics created by the X as opposed to being mutated outright.

* LovecraftLite: ''Fusion'' is a lot more overt with its horror elements than past ''Metroid'' games. The main antagonists are parasites that enter a host's body by phasing through their skin, killing them from the inside and effectively taking over their bodies. The B.S.L. has a much more suffocating atmosphere compared to previous Metroid games, thanks partially through the use of {{Railroading}} and the fact that Samus' weakened armor makes her take far more damage than previous ''Metroid'' games. Then there's the sheer horrifying creatures that prevail throughout the game, be it [[spoiler:Nightmare]] or the ImplacableMan that is the SA-X, an X mimicking Samus in her prime that Samus can't even ''hope'' to beat at the start of the game, resulting in many [[RunOrDie tense chase sequences]] that Samus escapes only by the skin of her teeth. However, despite this all, it never descends into outright SurvivalHorror, as Samus is still very much capable of holding her own against the X and ultimately [[spoiler:gains enough upgrades to finally take on and kill the SA-X.]]

* NiceJobFixingItVillain: Had the X left Nightmare and especially B.O.X. alone, Samus wouldn't have wandered off the path the AI planned for her [[spoiler:and would have been likely still in the dark about the Federation's attempts to weaponize the X and cloned Metroids until it was too late. Samus defeating B.O.X. and getting the Wave Beam grants her access to the Restricted Laboratory, which leads directly to her and Adam crashing the B.S.L. into [=SR388=] to kill all the X]].

* PunyEarthlings: The X don't have much interest in mimicking the B.S.L. human crew, since there were no armed soldiers present at the time of its outbreak, and the scientists lack any offensive capabilities the parasitic organisms can make use of. However, as they realize Samus is a potential threat to their species on the planet, they try to change strategies, mimicking a deceased crew member [[TakingYouWithMe to destroy the station with bounty hunter aboard]]. Their knowledge wasn't perfect though, and their meddling with the main boiler tripped the EmergencyBroadcast, alerting Samus and Adam to their plot.

* RaisingTheSteaks: The X not only infects people, but also alien wildlife on the B.S.L..

* {{Revenge}}: After being chased by the SA-X the entire game, it's only fair that you get your revenge before [[spoiler:destroying the B.S.L..]]

* {{Terraform}}: The B.S.L. space station is actually made from an asteroid moon that orbits planet [=SR388=]. The Federation recreates all the typical environments found on the world within it, thereby making a safer place for the researchers to do their work in studying the exotic alien creatures.

* VillainousRescue: [[spoiler:Samus has beaten an SA-X, plotted the B.S.L. Station on a collision course with [=SR388=], and is on her way to her ship to escape. But when she gets to the docking bays, the place is a mess, her ship is missing, and there is a huge shed Metroid skin on the floor. Suddenly, an Omega Metroid comes in and screeches at Samus. With one claw swipe, Samus is knocked down to one health, immobilized and completely helpless against the monstrosity... until the SA-X she defeated jumps in and tries to take it down. The Metroid quickly kills the SA-X, but this allows Samus to absorb its Core-X, regain the Ice Beam and kill the Metroid herself.]]

* ZombieApocalypse: The B.S.L. station succumbs to one courtesy of the X Parasites. It's a small taste of what could have happened to the entire galaxy had they got off the station. They kill whatever they infect and either pilot the bodies while applying BodyHorror or simply mimic them.

* NintendoHard: [[SlidingScaleOfGameplayAndStoryIntegration When the A.I. warns Samus she was significantly weakened from the X Parasites and the Fusion Suit is far less protective than her normal suit, it's not kidding.]] Even fully upgraded, Samus takes the highest amounts of damage in this game than any other ''Metroid'' game by far. This means you have to be far more careful and strategic even with basic enemies, and going in Franchise/{{Rambo}}-style like in other ''Metroid'' games is highly likely to get you killed. [[UpToEleven And that's not even going into the game's bosses,]] which there are more of than any 2D ''Metroid'' game to date.

* CheckPointStarvation: Once the power goes out, the only place you can save is your ship. Your next objective is a long slog through the core against powerful Kihunters, fully-powered Zebesian Space Pirates, and the Yakuza boss, all of which are [[DifficultySpike a huge step up]] from the enemies you've been fighting so far. Once auxiliary power is restored, a save point is right next door. It's even worse in 1% completion, because most of the enemies can kill Samus in one hit, including the boss, which is one of the contenders for the hardest boss in the game.

* GrayingMorality: This game paints the Galactic Federation as becoming as [[TheUnfettered Unfettered]] as the Space Pirates (though [[LostInTanslation in the Japanese version]], it's said to only be a subset of the group). Over the course of the game it's revealed [[spoiler:they have been weaponizing Metroids (for "peaceful applications," though Samus doesn't buy it since she knows how uncontrollable they can be) and that, based on the events on the B.S.L., the X Parasites (and SA-X specimen specifically) could also be potentially weaponized (which, again, sends Samus sideways that they would think that trying to cultivate such things wouldn't be a disaster waiting to happen. Not helped by the revelation that they were ''deliberately'' withholding upgrades from her so she couldn't kill the SA-X). She destroys their research in order to prevent any of this from coming to pass, but expects that she will be branded a traitor -- though Adam insists that at least one of them will understand.]]