Metroid (game)

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Metroid is an action-adventure title and the first installment of the eponymous Metroid series. The game was originally developed by both Nintendo R&D1 and Intelligent Systems and published by Nintendo. It first released for the Family Computer Disk System in Japan in 1986, and would later be ported to the Nintendo Entertainment System in North America in 1987 and in Europe and Australia in 1988. The game would eventually receive a remake for the Game Boy Advance, titled Metroid: Zero Mission.

The game's style, focusing on exploration and the search for power-ups that are used to reach previously inaccessible areas, has fundamentally influenced video game development including the Metroidvania genre. Its varied endings for fast completion times made it a popular game for speedrunning. It was lauded for being one of the first video games to have a female protagonist.


In the year 2003 C.C. (Cosmic Calendar), the leaders of various planets united in order to form a congress that became known as the Galactic Federation in an attempt to construct a fair and structured universe that would enable society to grow and prosper. Under the guidance of this new federation, the individuals of the planets began to associate with each other and a new civilization began to develop. Various leaps in technology for transportation were created, such as interstellar spaceships and society flourished through the use of such expansion.

At this time, Earth came into contact with individuals from these other worlds and the advanced technology that these people possessed was shared with the humans of Earth. All seemed well in this new society. However, devious groups known as Space Pirates began to attack the spaceships in the hopes of looting valuable goods from them and to strike fear in the hearts of the people. In order to counter these attacks, the Federal Bureau set up a new combat force known as the Federal Police. Yet the pirates were extremely difficult to battle in the depths of space, even with the advanced technology of the Federation. Thus, they recruited a group of courageous individuals who became known as Space Hunters, equipped with the best weapons available. The Federation provided huge financial bonuses to the Hunters in reward for hunting down and destroying the pirates.

In the year 20X5 C.C., the universe has continued to develop while battles still rage throughout space. Recent reports have indicated that a spaceship is traveling with a capsule containing an unknown life-force from the deserted planet of SR388. This planet has been attacked and seized by the Space Pirates. While research about this life-form, currently in hibernation, is incomplete, it is known that exposure to beta rays for 24-hours will cause it to multiply. Some scientists believe that this life-form may have been the cause of destruction of life on SR388. Scientists decide to call this being a Metroid and the mere thought of it being in the hands of pirates is utterly disturbing. If the pirates learn how to multiply it and use it as a weapon, the cost of lives could be overwhelming. The Federation launched search teams to find the pirates and were fortunate to discover that their base was located deep within the planet Zebes. However, none of the forces are strong enough to take the pirates down.

During this outside battle, operations to multiply the Metroid within the Space Pirates' headquarters were soon becoming a reality. Desperate for a solution, the federation decided that the only option left was to attempt to infiltrate Zebes and destroy the leader of the Space Pirates, Mother Brain. To make matters difficult, the structure of the planet Zebes is a natural fortress that consists of a large maze. Scattered throughout the maze are various traps and allies of the Space Pirates. This mission clearly requires a special individual to complete, and so the federation has selected the most dominating Space Hunter of the entire organization, Samus Aran.

Samus lands on the surface of Zebes and explores the planet, traveling through the planet's caverns. She eventually comes across Kraid, an ally of the Space Pirates, and Ridley, the Space Pirates' commander, and defeats them both. Eventually, Samus finds and destroys Mother Brain. A timed bomb is then placed to destroy the lair, and she must escape before it explodes.

Title screen[edit]

On the title screen, if Start Button is not pressed within around 30 seconds, a poorly translated synopsis of the game is shown:



Screenshot of Samus exploring a level

Metroid is an action-adventure game with some platforming and shooter elements. The player controls Samus as she travels through the planet's caverns and hunts Space Pirates. She begins with a weak power beam as her only weapon, and with only the ability to jump. The player explores more areas and collects power-ups that grant Samus special abilities and enhance her armor and weaponry, allowing her to enter areas that were previously inaccessible. Among the power-ups that are included in the game are the Morph Ball, which allows Samus to curl into a ball to roll into tunnels; the Bomb, which can only be used while in ball form and can open hidden floor/wall paths; and the Screw Attack, a somersaulting move that destroys enemies in its path.

In addition to common enemies, Samus encounters two bosses, Kraid and Ridley, whom she must defeat in order to progress. Ordinary enemies typically yield additional energy or ammunition when destroyed, and the player can increase Samus's carrying capacities by finding storage tanks and defeating bosses. Once Kraid and Ridley have both been defeated, the player can shoot their statues to open the path to the final area and confront the Mother Brain.

While Metroid is a single-player title, its box art advertises it as a "two player alternating game". Actual multiplayer in the Metroid series would not be introduced until Metroid Prime 2: Echoes.

There are five areas explored, in order of: Brinstar, Norfair, Kraid's Lair, Ridley's Lair, and Tourian.

Secret and hidden worlds[edit]

The hidden worlds of Metroid (also called secret worlds or hidden zones) are a feature of the game that arose unintentionally from the way the game uses level data. The hidden worlds are defined as sections of an area that exist beyond the normal confines of that area. Understanding this requires some understanding of how Metroid level data works. The map of Zebes is a singular entity; there are not different maps for each area. When an elevator shaft is used, the graphics and room data are changed to match that of the new area. Normally elevators are the only way to travel between certain areas of the map, but it is possible to use glitches or certain Game Genie codes to move through a ceiling or floor and enter another area of the map. This area will have a layout that exactly matches another normal area of the game (as it is the same part of the map), but the graphics and music will match the area Samus entered from, and the rooms themselves will be quite different. Accessing hidden worlds

A common way to access a hidden world is using the wall-jump glitch. To do this, Samus must open a blue door, and walk into it so that the door closes around her (but not so much as to walk through the door). Once Samus is in the door, the player must repeatedly alternate between pressing down and up, which will cause Samus to move upward through the ceiling slowly. The player must be careful not to press down very long, or else Samus will morph into a ball and get stuck. Once Samus reaches the top of the screen, the player must repeatedly hit the jump button, which if done in the right place, will cause the screen to scroll up until Samus is at the center. Obviously, this must be done in an area with vertical scrolling, or else no scroll will occur. The player must repeat these two steps until one of two things happens. Either another room will eventually appear at the top of the screen, or the scrolling will eventually stop. The new room may be part of a hidden world, if done at the right place, but it could also be part of the normal area.

There are also many Game Genie codes that players use to access and explore the hidden worlds. Many allow the player to do such things as travel through walls and floors, which can be necessary as the wall-jump glitch only allows Samus to travel up, and only at places where there's a door.

The hidden worlds must be entered at certain points, not just at any doorway. Any place on the map where one area meets another is a potential entry point, as long as the side they meet on matches the scrolling direction. There are also certain points where the player can return to the normal area from a hidden world, which may or may not also be entry points. Properties of hidden worlds

The hidden worlds work in different ways than the normal worlds. This is mainly due to the fact that the room data of the normal worlds was carefully laid out so as to work properly, while the hidden worlds were an accident and thus their room data is essentially random. This causes the hidden worlds to have certain strange properties.

One of these properties is directionality. In the normal game, every single door can be used both ways. In the hidden worlds, this is not always the case. There are many doors that lead directly into a wall and thus can only be accessed from one side (unless certain codes are used).

The hidden worlds also contain many scrolling errors. In the normal worlds, every door changes the scrolling from vertical to horizontal or vice-versa, and the same is true in the hidden worlds. However, the normal worlds are arranged so that every door also changes between a horizontally oriented area and a vertically oriented area. In the hidden worlds this is not the case, and a horizontal hallway may connect to another horizonal hallway with a door, causing a change to vertical scrolling which can stop further exploration or even prevent the player from returning where they came from. However, because the hidden worlds do not always have scroll stops in the right places (as the normal worlds stop scrolling at every doorway), some of these doors can be bypassed using cheat codes so that scrolling continues normally.

The hidden worlds also contain numerous trap doors, which are doors that do not lead to any actual room on the map. Therefore, when Samus walks through them, no scrolling occurs, and she becomes stuck. Some trap doors can be escaped, but this is rare.

Password system[edit]

Metroid was one of the first games to use a password system for saving game information between play sessions. The original Famicom Disk System version allowed saving of games on the disk, but the American release was in NES cartridge form (the Disk System, though originally planned for the American market, was never released there), and didn't implement battery-backed memory.

Nintendo released Metroid and The Legend of Zelda on the exact same day to compete against each other. After the title had shown lackluster sales, Nintendo of America denied the Metroid development team access to a battery-enabled save system that The Legend of Zelda had. As an alternative, the Metroid password system was born.[citation needed]

Metroid presents the player with passwords when Samus runs out of energy. Passwords are normally entered via the title screen, where the options "Start" and "Continue" are given; "Continue" leads to a screen where players can enter the password they received at the end of the last game. After doing so, they may continue playing, starting in the area where they ended the game, with the same power-ups and progress they had obtained. The password continuation feature was considered quite inconvenient and cumbersome by many gamers, and the sequel, Metroid II: Return of Samus, instead used a battery-backed save system. Metroid was the only game in the series to use a password system as its primary saving function.


Samus after using the JUSTIN BAILEY code.

JUSTIN BAILEY refers to a famous Metroid password that gives the player (nearly) all the power-ups needed to win the game, and allows the player to use Samus in a purple leotard rather than her armored suit. (The difference is purely visual; Samus has the same abilities and takes the same amount of damage from enemies that she would if she were wearing her suit.)

The password starts the player in Norfair as an armorless Samus with five Energy Tanks, 255 missiles (see below), the morphing ball, the Varia Suit, the Hi-Jump Boots, the Screw Attack, and the Wave Beam. Both mini-Bosses have been defeated and the path to the game's final area, Tourian, has been opened. The player must find the Ice Beam (this is required to defeat the Metroids in Tourian), and may opt to find a final Energy Canister before attempting to defeat Mother Brain.

A great deal of speculation surrounded the password. For instance, Justin Bailey was originally thought to be one of the creators of the game, but no such name appears in the game credits. It is also often said that the Justin Bailey code was a reference to an English or Australian term for a bathing suit. Allegedly, bathing suits are referred to as "bailies," so "Justin Bailey" would more accurately be rendered as "Just In (a) Bailey" or "Just In a Swimsuit," which is what Samus appears to wear when the code is used. However, no such slang for bathing suit actually exists (and Samus' outfit with this code is a leotard, not a bathing suit).

It was also rumored that the password violated Metroid's normal checksum verification, which would suggest that JUSTIN BAILEY was deliberately coded into the game. A website called The Metroid Database has attempted to debunk this myth using password generators:

...the JUSTIN BAILEY password is a total fluke. If you play around with Metroid's password system (something you can do with the Metroid Password Generator program, found in Fan Apps), you can come up with other names and words that work as passwords. The "Justin Bailey" code is one which was found early on and happened to work pretty well, so it became widely reported.[1]

Many players previously thought this code was the only way to play as an armorless Samus, but every password actually contains a flag indicating whether the player will be using armorless Samus or not. Armorless Samus is also a bonus that is normally available when you clear the game in under three hours. This applies only to the NES version.

One glitch with this code relates to the number of missiles Samus has at the start. Although the player starts with 255 missiles, the player's maximum number of missiles is 205; collecting a missile left behind by an enemy or collecting an upgrade will reduce the counter to 205 missiles.

There are some variations of the code, such as adding dashes in the bottom row instead of spaces. These will result in different starting points.


This code gives Samus infinite health and missiles, the Ice Beam, and every power-up in the game with the exception of Energy Canisters and Missile Expansions (and the Wave Beam, as Samus cannot carry both the Ice Beam and the Wave Beam). The player must still find and defeat both mini-Bosses. It is interesting to note that when this password is used, the Ice Beam's projectiles are represented by a different sprite than is used during regular gameplay or when using the "JUSTIN BAILEY" password. The sprite is the same one used to make up Samus' wave beam only rendered a different color. This combined sprite can be seen by selecting both ice beam and wave beam using a Metroid password editor.

There have been small debates on what the password stands for. Some think it refers to a "Narpas" sword, Narpa's Sword, or possibly even Narpas's Word. Others feel the password is properly read as "NAR Password," with several suggestions having been offered for the meaning of "NAR": an abbreviation for the name of the person who handled the conversion from the Famicom Disk System and designed the password system (Tohru Narihiro); an acronym for "North American Release"; or an acronym for "Not A Real", as in "Not A Real Password".

Alternate versions and re-releases[edit]

  • 1986 - Original release for the Famicom Disk System.
  • 1987 - Ported into the Nintendo PlayChoice-10.
  • 1987/1988 - Re-released for the Nintendo Entertainment System in North America, Europe, and Australia.
  • 1992 - Re-released for the NES as a Classic Series title.
  • 2002 - The original game can be unlocked in Metroid Prime by connecting the Nintendo GameCube–Game Boy Advance Link Cable to a copy of Metroid Fusion if it has been completed.
  • 2004 - Remade for the Game Boy Advance as Metroid: Zero Mission. The original game is also included as an unlockable for clearing any mode.
  • 2004 - The original game was re-released on the Game Boy Advance as part of the Classic NES Series (Famicom Mini in Japan). Like the original Famicom Disk System release, it has save functionality, replacing the password system from the Nintendo Entertainment System release.
  • 2007 - Ported to the Wii's Virtual Console.
  • 2011/2012 - Included as one of ten free NES titles for Nintendo 3DS units that were purchased before the August 12th price drop, as a part of the Ambassadors Program. In 2012, Metroid was re-released as a Virtal Console title on the Nintendo eShop.
  • 2013 - Ported to the Wii U's Virtual Console.
  • 2014 - A demo of Metroid is available as a Masterpiece in Super Smash Bros. for Wii U.
  • 2016 - Released as one of the 30 games included in the NES Classic Edition and its Japanese counterpart, Nintendo Classic Mini: Family Computer.
  • 2018/2019 - Re-released for the Nintendo Switch Online subscription service, and for the first time can be played with other players online. On December 12, 2018, a special version, Metroid: The decisive battle against Ridley!, was released. It starts Samus off at the battle against Ridley, with all of her items equipped. On February 13, 2019, another special version was released, Metroid: Samus Aran's ultimate arsenal, in which Samus starts the game with all of her items.

Famicom Disk System version[edit]

The save data screen in the Famicom Disk System version

Prior to the NES release, the game was released in Japan on the Famicom Disk System. Unlike the NES versions, this uses a three-slot save game system, similar to that of The Legend of Zelda's, rather than lengthy passwords. In addition, as armourless Samus was a bonus feature added for the NES port; it was not included in the FDS version. The FDS version instead adds a money bag image to the save slot, which indicates a completed game. It also has a lot less lag in the NES version.

The NES version of Metroid is one of the five Nintendo published games that contain a NES-SNROM-0x PCB chip that cannot save game data, suggesting that it was supposed to during some point in development.

The FDS version utilizes the system's wavetable sound channel for several sound effects, such as doors opening and larger monsters being hit. Five themes in the game also use the wavetable channel, adding an extra instrument to the music. In the NES version, this instrument was removed completely. The character initialization and item collection themes in most other Metroid titles were based on the themes from the FDS version of Metroid, however Zero Mission uses a combination of both the FDS and NES music.

Another notable difference between the FDS and NES versions is certain enemies' behavior is much more predictable in the NES version. Because the NES lacks the extra memory provided by the FDS, the behavior of certain enemies in the NES version was simplified. For example, Squeepts in Norfair jump out of the lava at one of three heights. In the FDS version, they can change their height each time they jump (low one jump, then high the next). In the NES version, once the enemy appeared, its jump height would be set to one particular value, and recalculated only when the enemy data leaves memory. This predictability removes a certain level of difficulty from the game.


Wii Shop Channel[edit]

"The first installment of the immensely successful Metroid series introduces us to the hideous title creatures and the slick, cybernetic bounty hunter Samus Aran. As Samus, your mission is to penetrate the space pirates' home planet, Zebes, and keep them from destroying the galaxy with the dangerous life-forms known as Metroids. Metroid has all the high-tech weaponry, creepy tunnels, and crawly alien creatures that anyone could ask for! With its deep and complex game play, excellent music, and a rare sense of setting, it establishes a frightening ambience that will haunt and entertain you for a very long time!"

Nintendo eShop[edit]

"The first installment of the immensely successful Metroid series introduces us to the hideous title creatures and the slick, cybernetic bounty hunter Samus Aran. As Samus™, your mission is to penetrate the space pirates' home planet, Zebes, and keep them from destroying the galaxy with the dangerous life forms known as Metroids. Metroid has all the high-tech weaponry, creepy tunnels and crawly alien creatures that anyone could ask for. With its deep and complex game play, excellent music and a rare sense of setting, it establishes a frightening ambience that will haunt and entertain you for a very long time."


For this subject's image gallery, see Gallery:Metroid (game).

Names in other languages[edit]

Language Name Meaning
Japanese メトロイド