Metroid Fusion

Metroid Fusion (also known as Metroid 4 (メトロイドフュージョン, Metoroido Fyūjon, and referred to as Metroid IV during production) is currently the last game chronologically in the Metroid series. It is also the first Metroid game released on the Game Boy Advance. It, along with Metroid Prime, is the first Metroid game released in eight years since Super Metroid in 1994. It occurs after the sequel, Metroid: Other M.

The gameplay of Metroid Fusion is quite different from other Metroid games as it is very linear; it also introduces a non-playable cybernetic entity who provides Samus with specific objectives, thus making sequence breaking and exploration nearly impossible.

Story
The game begins with Samus Aran helping Biologic's research team on planet SR388. Eventually, a Hornoad confronts them and is killed by Samus. However, a globular yellow organism emerges from the Hornoad as it is destroyed and enters Samus's body.

Feeling no initial effects, Samus continues escorting the researchers and completes the assignment. On the way back to the laboratory, however, Samus loses consciousness, and her gunship crashes into an asteroid. The ship's emergency systems automatically ejected Samus' escape pod, saving her from the crash, but her gunship is completely destroyed. Samus is quickly attended to by a medical crew, who discover that the creature that entered her body on SR388 was actually a parasitic organism that they soon named X.

The organic components of Samus's Power Suit had become so integrated with her system that it could not be removed while she was unconscious. Large portions of her infected suit had to be surgically removed, dramatically altering its appearance. However, the X in Samus's central nervous system were too embedded to be removed safely; Samus's chances of survival were less than one percent.

Metroids are the only known predator of the X; however, since Samus destroyed all the Metroids on SR388 in a previous mission, the X were able to multiply unchecked. Seeing this as the key to curing her, doctors proposed using a Metroid cell from Samus' dead Baby to make an anti-X vaccine. Apparently, the Federation had managed to preserve a cell culture from the Baby that saved Samus while she was on Zebes a second time. The serum was prepared and injected without delay, completely eradicating the X. There were, however, two side effects: Samus could no longer be hurt by normal X and could even absorb them to replenish health and ammunition, but she also inherited the Metroids' vulnerability to cold.

Upon recovering, Samus is sent to investigate an explosion on the Biologic Space Laboratories research station, where the specimens from SR388 and the infected pieces of her Power Suit are being held. Once she arrives at the station, Samus immediately heads to the Quarantine Bay, where she encounters and kills a Hornoad that has been infected by an X parasite. Samus speaks with her new gunship's computer (who she has named Adam as it reminds her of a former CO) and learns that the specimens brought back by the field team have become infected by the X. The computer also reveals that the X can use the DNA of its prey to create a perfect copy, meaning any organic life on the station may also be infected.

As she continues to explore the station, Samus discovers that the X have used the infected portions of her Power Suit to create a copy of Samus herself, dubbed the SA-X (or Samus Aran-X). Since the SA-X arose from Samus's fully-upgraded Power Suit, it has all of her powered-up abilities, as evidenced by it using a Power Bomb to escape the Quarantine Bay. By exploding the bomb, the SA-X also destroyed the capsules holding the X specimens, releasing them all into the station. Well into her investigation of the station, Samus stumbles upon the facility's Restricted Lab. Here, she finds dozens of infant Metroids and several more Metroids in various stages of maturity, all in stasis; these were the results of a cloning project of which Samus was not previously aware. Shortly after Samus discovers them, the SA-X attempts to destroy its predators, allowing the Metroids break free and activating the emergency fail-safes. Samus barely escapes before the lab locks down completely and is jettisoned from the station, exploding over SR388.

After the incident at the Restricted Lab, Samus speaks with her ship's computer, who is angry about the discovery and subsequent destruction of the Metroids. The computer explains that the Federation had been secretly working on a Metroid breeding program, for "peaceful application". The computer reveals that the station's SRX environment, a replica of the SR388 ecosystem, was ideal for raising Alpha, Gamma, Zeta, and even Omega Metroids. The research uncovered techniques for rapid growth, allowing an infant grow into an Omega Metroid in mere days. However, the X discovered the research through the memories of an X-infected crew member and destroyed the project. Much to Samus's surprise, the computer also mentions that the SA-X has been reproducing asexually and there are no fewer than 10 aboard the station.

Later, the computer tells Samus that she has caused enough damage and instructs her to leave the rest of the investigation to the Federation. Apparently, the Federation has taken an interest in the X and SA-X and believe that this life-form has endless applications. Samus, having seen the SA-X's destructive capabilities firsthand, is strongly against this. She is convinced that the X will overwhelm the Federation troops as soon as they land, absorbing their powers and knowledge in the process. If this happens, they could easily spread throughout the galaxy and "galactic civilization will end."

As an alternative, Samus decides to activate the station's self-destruct mechanism in order to destroy the X, risking her own life in the process. However, her ship's computer has locked Samus in a Navigation Room, as the Federation has ordered it to keep her confined until their arrival. Desperate, Samus yells at the computer: "Don't let them do this. Can't you see what will happen, Adam?" Puzzled at the use of the name, the computer inquires as to who this Adam was. Samus reveals that he had been her previous commanding officer and had died saving her life. Apparently moved by Samus's revelation, the computer agrees with the plan, and suggests that if Samus were to alter the station's orbit, then she might be able to include the planet in the explosion, thus ensuring the destruction of the X on SR388 as well as those on the station. At this point, Samus realizes that her ship's computer truly is Adam Malkovich, whose personality had been uploaded to a computer prior to his death.

Samus hurries to the Operations Room, where she is confronted by an SA-X. She manages to defeat it, but its Core-X escapes before she can absorb it. Ignoring its escape, Samus initiates the self-destruct sequence and hurries back to her ship. However, she finds the docking bay in ruins and her ship gone. Before she can react to the situation, an Omega Metroid appears, apparently having escaped from the Restricted Lab before its destruction and grown to full size in record time. Samus possesses no weapon capable of damaging the Metroid, and a single swipe of its claw reduces her energy reserves to single digits. As the Omega Metroid prepares to finish her off, the SA-X returns, and attacks the Metroid with its Ice Beam, injuring it. However, it was greatly weakened from its fight with Samus and is quickly defeated by the Metroid. This time, the Core-X hovers over Samus, allowing her to absorb it and obtain the Omega Suit as well as the Ice Beam. Using her regained abilities, Samus fights and kills the Omega Metroid after a fierce struggle. After the battle, Samus's ship reenters the bay, having been piloted by the computer, Adam, and the same Etecoons and Dachoras she saved on the previous mission to Zebes and later on the Habitation Deck.

As Samus leaves the station, it is shown crashing into SR388, destroying both the station and the planet, ridding the universe of the X forever.

Reflecting on her actions, Samus doubts people will understand why she destroyed the X, nor will they realize the danger that was barely averted. Samus believes she will be held responsible for defying the Federation, but Adam comforts her, telling her: "Do not worry. One of them will understand. One of them must." A final reflection, Samus goes on to say: "we are all bound by our experiences. They are the limits of our consciousness. But in the end, the human soul will ever reach for the truth... This is what Adam taught me."

Gameplay
As mentioned before, Metroid Fusion is much more linear than other games in the series. The gunship's computer gives Samus objectives throughout the game, and its ability to lock and unlock doors depending on the objective renders exploration outside of the objective's immediate area nearly impossible. This dictates the sequence of acquiring Power-ups, defeating enemies, and reaching certain areas. Therefore, the only exploration that can be done at a given time is limited almost exclusively to secret rooms along the way to each objective.

The environments in Fusion also change throughout the game in much more radical ways than in other games in the series. For example, some corridors become permanently blocked by explosions, parts of the research station are completely destroyed, and new creatures appear in previously explored areas. Some gameplay elements differ significantly as well, including disabling mid-air bomb jumping and other methods commonly used to perform Sequence Breaking.

Some new gameplay mechanics have been added since Super Metroid to make up for the disabled ones, though. For instance, Samus is able to grab on to ledges, which would later become the Power Grip upgrade in Metroid Zero Mission. In place of the Grapple Beam, Samus can now climb special ladders and "monkey bars" to span large heights and gaps.

Samus spends most of the game being stalked by the SA-X, who appears unexpectedly in various locations. Due to Samus having the Metroid vaccine, she is very susceptible to the SA-X's Ice Beam -- each hit costs more than an entire energy tank; once she is frozen, the SA-X will hit Samus with a missile, damaging her even more. As a result, until the final battle with the SA-X, the only thing the player can do when the SA-X shows up is to run and hide.

Much of the gameplay also involves Samus downloading data as a method of obtaining Power-ups. Since she is using the Fusion Suit, most of her equipment has been rendered unavailable, requiring Federation hardware teams to design new versions of the upgrades and transmit them to Data Rooms on the station. The Power-ups that Samus does not obtain in this way are acquired by absorbing the Core-X left behind by defeated bosses.

Almost all of the creatures in the game are actually X parasites mimicking other lifeforms. Creatures are usually reduced to floating X cells when they are destroyed, and Samus can absorb these to replenish her lost energy and missiles. However, if Samus does not absorb them, they can re-form into new enemies or disappear entirely. Some monsters can also absorb additional X parasites, evolving into newer, more powerful forms.

Graphics
The graphics are very similar to Super Metroid ' s and are rendered in 2D. The overall graphics and animations are more detailed, however. The game is a side-scroller, so, like the rest of the 2D Metroid games, all of the action is displayed from a side-on angle. Metroid: Zero Mission uses a highly modified version of Metroid Fusion's game engine.

Equipment
Samus begins the game with little equipment. Since her Power Suit had to be removed and replaced with the Fusion Suit, almost all of her abilities were lost. She must retrieve them through either downloading the data from terminals scattered throughout the station, or by absorbing certain powerful X-parasites.

The Jump Ball and High Jump abilities are combined into one item. Her regular orange Power Suit is replaced by the organic-looking yellow and blue Fusion Suit. Each missile upgrade stacks instead of being a separate kind of weapon. As a result, any kind of missile — normal, super, ice, or diffusion — will only ever use up one of Samus's total ammo count. The same stacking method applies to beams: if Samus gets a new beam, they all apply at once and need not be switched. Power Bombs also have a blast radius that takes up the whole screen and reveals the presence of unusual blocks, making up for the absence of the X-Ray Scope.

Adam Malkovich
Adam was Samus's commanding officer during one of her assignments with the Galactic Federation. Very little is known about this mission or about Adam himself, other than that Samus has great respect for him and that he gave up his life to save Samus. In the game, Samus stated that Adam called her "Lady" on her missions; if any one else had said it, it would have sounded sarcastic, but from him, it was respectful.

Special features
Owners of both Metroid Prime and Metroid Fusion can unlock new features in Metroid Prime using the Nintendo GameCube Game Boy Advance Cable. If you complete Metroid Prime, you can unlock Samus's Fusion Suit for use in Prime; if you complete Metroid Fusion, you can, depending on the game version, unlock an emulated version of either the original FDS version or the NES port of Metroid. There is also a bonus to be had by linking to Metroid: Zero Mission — the entire Fusion gallery of post-ending pictures is unlocked in Zero Mission, including the extra ending images from the Japanese version of Fusion which chronicle Samus's early years, as well as some additional concept art.

Reception
Metroid Fusion was very well received. The main criticism came from the game being so linear. According to Metacritic, the average rating for the game is 92.

Beta Versions

 * 2001 Video #1
 * 2001 Video #2
 * Prerelease video #1
 * Prerelease video #2
 * High quality screenshots

Trivia

 * The Metroid Fusion instruction manual states that Metroids were actually created by the Chozo to prevent the spread of the X parasite and that the word "Metroid" roughly translates to "ultimate warrior" in the Chozo language.
 * Metroid Fusion is the only Metroid game that can be completed with 0% of the items (only the capacity upgrades count towards the percentage, not the Power-ups themselves). Previously, the minimum was thought to be 1%, as a capacity upgrade in PYR is impossible to avoid. With frame-perfect timing, however, it is possible to take a different route. This feat has yet to be accomplished on an original cartridge.
 * A selectable suit costume resembling the Fusion Suit appears in Super Smash Bros. Brawl.
 * The final escape for Metroid Fusion is strikingly similar to the escape scene in Aliens, the movie. Both involve the main characters stranded without escape from a building/station that is about to self-destruct, and just at the last moment, their spaceships re-dock at the landing site to rescue them from the impending explosion. Seeing how the series was inspired by the Alien franchise, it's safe to say that this may have been the inspiration for the final escape in the game. Also the final battle between the Omega Metroid and Samus is similar to the final battle between Ripley and the Queen alien from the movie.
 * Near the end, Samus's eyes are visible for the first time in a very long while. Her visor appears to have digital information displaying at the time.
 * The part near the end where the Federation reveals that it has been secretly breeding Metroids may be based off of the Weyland-Yutani corp. from the Alien franchise, as it also had lied to the main protagonist, Ellen Ripley, about its intentions with the Xenomorphs.
 * Certain aspects of this game are similar to the movie Alien Resurrection. The main character has DNA of the antagonist alien species (Ripley has Alien DNA and Samus has Metroid DNA), members of the normally hostile alien species don't attack the main character due to their possibly thinking that the main character is one of them, and both "companies" resurrect the franchise's previously extinct primary alien species.
 * If Samus gets to the Reactor Silo after starting the Propulsion Sequence, the path to it contains demolished debris, blocking the way.
 * Right after Adam dismisses Samus to start the Propulsion Sequence, if she explores the remains of the BSL once more, nearly all the X are gone. This may be due to the overgrown Omega Metroid roaming the station while Samus was confined in the Navigation Room.
 * This is a link showing how to do one of the very few sequence breaks in the game:
 * This game and Metroid Prime are the only two games in which the player obtains the Missile upgrade before the Morph Ball. In all the other games Samus is already in possession of the Morph Ball or it is the first to be obtained. It is also the only game where the Plasma Beam is acquired before the Wave and Ice Beams.
 * This is one of three Metroid games that does not have a Map Station (discounting Metroid and Metroid II: Return of Samus, which have no map system at all); the others being Metroid Prime Hunters and Metroid: Other M. Navigation Rooms double as Map Stations in this game, as the map for the area is automatically downloaded when Samus first enters the sector.
 * The game's American commercial names a location called the "Metroid Fusion Bio-Lab".
 * In one of the game's cutscenes, the docking bay doors have "B.S.L Space Laboratory." It is believed by some that the acronym gives it the redundant name, "Biologic Space Laboratories Space Laboratory".
 * In the Metroid series's timeline, Fusion is Samus's final appearance, as Other M takes place between Super Metroid and Metroid Fusion.
 * Metroid Fusion has the same number of bosses as Metroid: Other M, with a total of thirteen.