Nintendo's Metroid famously pulls from the Alien film franchise. Bounty hunter Samus Aran is an early example of a capable female protagonist similar to Sigourney Weaver's Ellen Ripley, and Samus' most recurring foe is a Space Pirate named Ridley - clearly mimicking acclaimed director Ridley Scott. Both franchises have also straddled the line between atmospheric horror and high-octane action. For every Metroid Fusion that harkens back to the tense thrill of being stalked by an unstoppable threat in deep space, games like Metroid: Other M focus on blasting that opposition away ala Aliens.

Metroid Fusion is officially 20 years old, yet is seemingly more relevant than ever. Last year, Nintendo made waves with the release of MercurySteam's Metroid Dread, a direct sequel to Fusion that emerged following decades of sporadic development (even being referenced within 2007's Metroid Prime 3: Corruption). Dread did not capture quite the same atmosphere as Fusion, but it advances many lingering plot threads. In fact, Fusion will undoubtedly still have an impact on adventures well beyond Dread.

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Where Metroid Fusion Fits in the Series' Timeline

Metroid Fusion Research Station

The overall timeline of Metroid games is complicated by Team Ninja's Other M and Retro Studios' Prime trilogy, among others, but the core of this franchise is five releases starting with 1986's Metroid on NES. After Samus defeats Mother Brain on Planet Zebes, Metroid 2: Return of Samus on Game Boy follows her journey to the Metroid homeworld SR-388 on a mission to eradicate the dangerous alien species. One baby Metroid survives and imprints upon Samus, which she brings to a Galactic Federation base.

This is where the series' arguably most famous entry, Super Metroid, begins. The baby Metroid is kidnapped by Ridley and brought back to Zebes so that Space Pirates can clone more. After once again defeating Mother Brain with the sacrifice of a powered-up baby Metroid, Samus goes about her galactic business. Her story picks up again in Fusion when she encounters the hostile X Parasite during a research mission on SR-388.

It is ultimately revealed that the ancient Chozo people developed Metroids to act as a predator for the X, which perfectly duplicate any creature they assimilate. Samus is only saved from her infection via the use of a vaccine developed using the baby Metroid's DNA, but this leaves her with new problems like a weakness to ice. The bounty hunter destroys the Biologic Space Laboratories (BSL) research station as it becomes overrun by X, one of which mimics her power armor to become the threatening SA-X. Dread then deals with a tip that more of these parasitic entities have appeared on remote Planet ZDR following their supposed eradication.

Metroid Fusion Emphasizes the Series' Alien Horrors

Metroid Fusion close-up of SA-X's face

In a 2022 interview with the YouTube channel DidYouKnowGaming, Metroid Prime's original lead developer John Whitmore said Fusion began development following Prime's well-received announcement at Space World 2000. It was designed to release alongside Prime, Samus' foray into being a first-person shooter protagonist; appealing to more traditional fans. The Prime trilogy went on to be a popular interpretation of the series, but Fusion was unique in that it launched eight years after Super Metroid before serving as the last mainline entry for 19 years.

All 2D Metroid games prior to Fusion followed a similar formula, dropping players into a dark alien world that unravels as Samus gains new abilities to make exploration and combat easier. Horror is ever-present, particularly in Metroid 2 where SR-388 becomes more desolate and unnerving as Samus commits Metroid genocide. However, Super Metroid seemingly leaned more into Samus as a conquerer of Zebes in her return trip, likely in no small part thanks to the SNES' enhanced graphical prowess and controls.

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Metroid Fusion is overtly a horror game, trapping Samus in a claustrophobic research station where all life (including other humans) has been eradicated and replaced by parasites capable of exaggerating their shapeshifting forms. Criticism has been levied against Fusion for being more linear than the infamously open-ended Super Metroid, but this design often enhances the tense BSL station, which has cinematic hostile encounters around every turn.

Then, of course, comes the SA-X. Alien parallels are perhaps best exemplified by this antagonist, which stalks Samus around the station using every Super Metroid weapon she lost (and can partially reclaim by defeating bosses). Fusion's linearity builds a handful of stealth sequences in which Samus has to hide around dark corners and vents while SA-X moves about the room, ready to pounce like a Xenomorph in 2014's Alien: Isolation. Dread's E.M.M.I. try to recapture some of SA-X's magic, but fall short in the eyes of many fans.

Metroid Fusion's Additions Will Carry Well Beyond Dread

Samus wearing the Metroid Suit in Metroid Dread

Despite the core 2D Metroid franchise going dormant for nearly two decades after Fusion launched, it carried a lot of the series' identity forward. It is one of the Game Boy Advance (GBA) titles included in the 3DS Ambassador Program, which offered a number of free games to those who bought a 3DS handheld prior to its price drop in 2011. Metroid Fusion and a remake of the original game, Metroid: Zero Mission, also released on the Wii U virtual console (both GBA titles spiked in sales around the launch of Metroid Dread).

Fusion also played a huge part in the design of Metroid: Other M, which chronologically takes place prior to Samus' escapades on the BSL station. The oft-derided Team Ninja spin-off dives deeper into the relationship between Samus and her former commanding officer Adam Malkovich, who is introduced in Fusion as the nickname Samus gives to a chatty AI. Other M also brings back the gravity-controlling biomechanical boss Nightmare, the subject of a particularly horrifying Fusion sequences as it distort the screen and literally melts into sludge as Samus deals damage.

However, Fusion's direct sequel Dread shows the full impact of the 2002 game. Planet ZDR is infested with X Parasites, but this reveal is merely how Chozo warrior Raven Beak draws Samus in to take advantage of the latent Metroid DNA that fused with her body. By the end of the game Samus transforms into a half-Metroid with the power to drain other beings of life. How future titles will play with this twist remains to be seen, but Fusion will continue to have a lasting presence as Nintendo jump-starts Samus' next saga.

Metroid Fusion is available now on GBA and Wii U.

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