《銀河戰士 融合》（Metroid Fusion）是該系列的第四部作品，於2002年11月在Game Boy Advance（GBA）平台上推出。由任天堂開發，以其緊湊的劇情敘述、精緻的操作設計以及強烈的氛圍而廣受好評。在延續系列核心玩法的同時，加入更多劇情導向的元素與現代化的設計，成功吸引新玩家，也贏得系列老粉絲的讚譽。

故事發生在《超級銀河戰士》的事件之後，主角薩姆斯·亞蘭（Samus Aran）在SR388星球執行任務時遭遇新型寄生生物「X寄生」（X Parasite）。這種寄生生物侵入宿主體內後會摧毀其生命力，並模仿宿主的外觀與能力。薩姆斯在感染後性命垂危，但銀河聯邦的科學家使用銀河戰士幼體的細胞製造出疫苗，成功挽救她的生命。儘管如此，她的裝甲與部分能力卻因感染被永久損壞。

恢復健康後，薩姆斯被派往名為B.S.L.（Biologic Space Laboratories）的太空研究站調查「X寄生」的擴散情況。然而，事情並不簡單。研究站內的X寄生快速繁殖，甚至模仿薩姆斯最強的形態（即「SA-X」），成為她最強大的敵人。隨著調查的深入，發現銀河聯邦試圖利用X寄生作為生化武器的陰謀，並計劃繁殖銀河戰士進行軍事用途。薩姆斯意識到B.S.L.研究站和SR388星球已經成為巨大威脅，最終決定毀滅研究站並將其撞向SR388星球，徹底摧毀這些危險的生物。在最終決戰中，她成功擊敗SA-X，並在銀河戰士幼體所賜予的力量幫助下，脫離即將毀滅的研究站。

劇情中貫穿薩姆斯與人工智能「亞當」（Adam Malkovich）的互動，亞當是研究站內的導航電腦，也是薩姆斯已故指揮官的虛擬化身。他的存在不僅推動劇情進展，也深化薩姆斯的個人情感層面，為系列帶來了更多人性化的一面。核心玩法延續系列一貫的動作冒險與探索元素，但加入現代化的改進和更強的敘事驅動。依舊採用2D橫向捲軸的形式，穿越迷宮般的研究站，逐步獲得新的能力與武器，以解鎖新的路徑並面對強大的敵人。

薩姆斯在本作中的操作感更加流暢，動作與射擊更具精準度。經典的裝備與能力如螺旋球（Morph Ball）、飛彈（Missiles）和能量波束（Power Beam）悉數回歸，通過擊敗X寄生模仿的頭目來重新獲得這些能力。特別值得一提的是，可以吸收X寄生以恢復生命與補充武器能量，這成為遊戲的重要機制。與系列過去作品相比，導航系統更加線性。會定期接受亞當的指引，並獲得明確的任務目標。這種設計雖然減少玩家迷路的可能性，但也使探索的自由度有所降低。然而，氛圍依然緊張而壓迫，特別是在SA-X的追捕場景中，必須小心躲藏，避免被這個強大敵人發現，這種高壓的生存恐懼成為本作的一大特色。

場景主要集中在B.S.L.研究站內，該站被分為多個區域，每個區域都有不同的生態環境，如熱帶森林、冰凍地帶、火山熔岩區等。這些區域的設計獨具特色，結合環境挑戰與敵人配置，提供豐富的探索體驗。每個區域都有獨特的頭目戰，這些頭目多數是被X寄生感染並模仿的強大生物，它們擁有獨特的攻擊模式與弱點，要熟悉其行為模式並善用薩姆斯的能力才能擊敗它們。此外，迷宮中還隱藏大量的能量罐（Energy Tanks）、飛彈升級和能力強化模組，鼓勵玩家仔細探索。氛圍營造極為出色，B.S.L.研究站內的燈光效果、背景音樂與敵人設計共同營造一種孤獨與緊張的感覺。特別是在SA-X出現時，陰森的音效和危險的追逐場景讓人感到高度壓迫。這種恐怖元素與動作冒險結合，極大地提升遊戲的代入感。

自發售後獲得廣泛的好評，被譽為GBA平台上最出色的作品之一。評論家稱讚遊戲緊湊的劇情敘述、優秀的操作手感與緊張的氛圍，並將其視為系列的卓越延續。特別是SA-X的設計和與亞當的互動，為遊戲增添新的層次感。然而，也有部分玩家對整體的線性設計提出批評，認為這種方式削弱該系列以往強調的自由探索特性。即便如此，這改變也讓新玩家能更輕鬆地上手，從而吸引更廣泛的受眾。

銷售方面，該作表現優異，全球銷量超過160萬，鞏固該系列在動作冒險類型中的地位。成功為後續作品鋪平道路，並為系列的劇情與角色發展奠定基礎。至今，仍被視為系列中的經典之作，並被眾多玩家視為童年的美好回憶。

Metroid Fusion, the fourth installment in the Metroid series, was released in November 2002 for the Game Boy Advance (GBA). Developed by Nintendo, it received critical acclaim for its compact storytelling, refined gameplay mechanics, and intense atmosphere. While retaining the core gameplay elements of the series, it introduced more narrative-driven features and modernized design, successfully attracting new players and earning praise from longtime fans.

The story takes place after the events of Super Metroid. The protagonist, Samus Aran, encounters a new parasitic organism called the "X Parasite" while on a mission to planet SR388. This parasite invades hosts, draining their life force and mimicking their appearance and abilities. After being infected, Samus faces a life-threatening situation but is saved by a vaccine created by Galactic Federation scientists using cells from the infant Metroid. However, the infection permanently damages her suit and some of her abilities.

After recovering, Samus is dispatched to the Biologic Space Laboratories (B.S.L.) space station to investigate the spread of the X Parasite. What initially appears to be a straightforward mission becomes increasingly complex as the parasite rapidly proliferates within the station. It even mimics Samus's most powerful form, creating the formidable enemy "SA-X." As Samus delves deeper into the investigation, she uncovers the Galactic Federation's sinister plans to weaponize the X Parasite and breed Metroids for military purposes.

Realizing the catastrophic threat posed by the X Parasite and the experiments on SR388, Samus decides to destroy the B.S.L. station, crashing it into the planet to obliterate the dangers entirely. In the climactic confrontation, she defeats SA-X and escapes the doomed station with the help of the power granted by the infant Metroid.

The narrative is enriched by Samus's interactions with an AI named Adam Malkovich, a navigation computer modeled after her late commanding officer. Adam not only drives the story forward but also deepens the emotional dimension of Samus’s character, introducing a more humanized perspective to the series.

The gameplay maintains the action-adventure and exploration elements that the series is known for, while incorporating modern improvements and a stronger narrative focus. Presented in a 2D side-scrolling format, players navigate the maze-like space station, acquiring new abilities and weapons to unlock new areas and defeat formidable enemies.

Samus’s controls in this installment are smoother and more precise, enhancing her movement and combat capabilities. Classic abilities like the Morph Ball, Missiles, and Power Beam return, along with new mechanics such as absorbing X Parasites to restore health and replenish weapon energy. This absorption system becomes a core gameplay feature.

Compared to previous entries, the navigation system is more linear. Players frequently receive guidance from Adam and are given clear mission objectives. While this reduces the likelihood of getting lost, it also diminishes the series’ hallmark emphasis on open-ended exploration. Nonetheless, the game retains its signature tension, particularly during sequences where players must evade the relentless SA-X. These high-stakes encounters heighten the game’s survival-horror elements.

The B.S.L. station serves as the primary setting, divided into various zones with unique ecosystems such as tropical forests, icy landscapes, and volcanic areas. Each zone features distinct environmental challenges and enemy configurations, offering a diverse exploration experience.

Boss battles are a highlight, with most bosses being powerful creatures infected and mimicked by the X Parasite. These encounters require players to analyze attack patterns and strategically utilize Samus's abilities. Hidden upgrades, including Energy Tanks, Missile expansions, and ability enhancements, encourage thorough exploration of the station’s labyrinthine layout.

The game excels in atmosphere, with lighting effects, haunting music, and enemy design working together to evoke feelings of isolation and tension. The ominous sound effects and perilous chase scenes involving SA-X amplify the sense of dread. This fusion of horror elements with action-adventure gameplay creates an immersive experience.

Upon its release, Metroid Fusion garnered widespread acclaim and is regarded as one of the finest titles on the GBA. Critics praised its tight narrative, polished controls, and gripping atmosphere, considering it a worthy continuation of the series. The SA-X design and interactions with Adam added depth and layers to the game. However, some players criticized its linearity, arguing that it reduced the freedom of exploration that characterized earlier entries. Despite this, the streamlined approach made the game more accessible to newcomers, broadening its audience.

In terms of sales, Metroid Fusion performed exceptionally well, selling over 1.6 million copies worldwide. It cemented the series’ reputation in the action-adventure genre and laid the groundwork for future installments, shaping the trajectory of the franchise’s story and character development. To this day, it remains a beloved classic, cherished by fans and remembered fondly as a highlight of their gaming experiences.