Metroid

The story of one girl and her highly advanced power suit borrowed from a dead civilization of birdmen. Also, there's no map. Have fun!

Debug Features
The NES version of Metroid contains a secret password, which enables several debugging features (the zeroes are optional): ("NAR" refers to Toru Narihiro, the programmer who converted the game from the FDS disk format to standard ROM)

This will send you to the start of the game with the following debugging features enabled:
 * Infinite health (the tens digit of your health never changes; you can still get hit and take damage, it just won't have much of an effect)
 * Infinite missiles (though you technically don't have any missile containers; this can lead to a crash in Tourian, as noted below)
 * Ice Beam equipped (this uses the Wave Beam's graphic with the Ice Beam's palette, which never happens normally)
 * All items obtained (sans missile containers and energy tanks)

PROTIP: If you intend to beat the game with this password, it would be wise to pick up at least one missile container first. If you kill a Metroid without obtaining a missile container, and it attempts to drop a missile pickup, the game will freeze. Alternatively, you can just avoid killing Metroids altogether. This glitch was not fixed in any of the later rereleases of the game (e.g. the one included with Metroid Prime), possibly because Nintendo is unaware of the code's existence.

Inaccessible Rooms
There are three rooms in the game's map that are inaccessible, all in Norfair. They're copies of rooms that exist elsewhere in the game.

The hall at the bottom of this screen isn't connected to anything and thus can't be entered.

The room to the left is, once again, not connected to anything.

The room at the bottom of the long shaft on the right side of Norfair does not connect to anything.

Unused Rooms
In addition to the rooms identified above, which are present on the map but can not be accessed, there are five rooms defined in the game that appear nowhere on the map.

This unused room is similar to one of the rooms which is visible in the game. It has no enemies, but it does have a door.

This room has an item sphere generally held by statues. The sphere behaves like the ones held by statues (reappearing a few moments after being shot), but its contents are empty.

This room is present in the room data for Kraid's hideout, but the pointer that should reference it instead points to the data for the next room. The room has no door bubbles and is not used in the game.

The hallway and elevator shaft are standard rooms in every level. The halls are used for palette transitions, and since these don't occur in Kraid's hideout, this unfinished hall does not appear anywhere on the map.

Like the hall in Kraid's hideout, this Tourian hall is unfinished and unused. Interestingly, this hall uses different graphics from the others. The dark gray squares inside the hall appear in front of Samus.

Save Function
Interestingly, opening up the Metroid cart reveals that it uses an NES-SNROM-0x PCB (x indicates the board revision). Among the five games that Nintendo published using this board, three of them used the battery backup space. Releases of Metroid outside of Japan did not have a save feature and opted for a password system, instead, as the Famicom Disk System version(s) relied on disk backup. The other game that didn't use a battery was Kid Icarus, which shared a similar transition from Japan. Metroid was the first NES title to use the SNROM board, which implies that they intended to have battery backup, but ultimately left out the battery, perhaps as a cost-cutting measure.

Unique Left/Right Sprites
Unused tiles for Samus, as well as the orientation of the used tiles, indicate that Samus was originally going to have unique sprites for facing left and right. There are tiles for running and shooting while running. The feet for the standing pose and gun for the upwards-aiming pose are also mirrored compared to the rest of the tiles in the pose. In the final version of the game, Samus uses the same sprites for both directions, which means her gun arm switches between her left and right arms.

Oddly enough, the alternate tiles for suitless Samus seem to be from an earlier version of her running animation. Her hand is held in a different position, her hair is less messy as it waves, and her chest is flatter. As suitless Samus is unique to the later cartridge versions of the game, it's possible that the artist who initially drew the tileset was not aware that the alternate tiles were unused.

Interestingly, these unused tiles for both sets of unused tiles are located in the same location in the tilesets. This may very well be due to the confusing layout of the tiles. Her gun is also one pixel longer, making it more closely resemble her normal gun.

Alternate Foot


One tile, present in both Samus tilesets, is what appears to be an alternate foot for the facing-the-screen pose. Shown in this image are various attempts at reconstructing how the tile may have been used.

Version Differences
The game went through a number of changes when it was ported from its original Famicom Disk System format to the NES cartridge format. While most of the changes were cosmetic in nature, some were an unavoidable result of the change from rewritable media to static ROM.

Title Screen
The Japanese version features a much nicer title logo compared to the rather plain appearance of the NES version. Besides the redrawn logo, there's spacing added between copyright and year and a trademark symbol added.

Select Screen
The Japanese version features a File Select screen with three save slots, like The Legend of Zelda. You can also see how many hours you have spent on your mission, where one hour of gameplay represents one 'day.' The NES version uses a password system instead.

Zero and dotted 'O'
In order to make it easier distinguishing the two for the added password system, the zero was slightly altered to appear more like a slashed zero and the letter 'O' was dotted. What's a little odd is that the dotted 'O' ended up being used in all the text throughout the game except for the ending and end credits.

Game Over
In the NES version, the "Game Over" text was moved higher in frame and the spacing between the words was reduced.

The text was also given a colour palette that varies depending on which area in the game you die in.

If you lose the game, or decide to quit, the FDS version provides you with an option to save your progress. The NES version, instead, gives you a password.

Cleared Game


The FDS version adds "money bag" graphics to the save slot, which indicates a completed game. The faster you finish your mission, the bigger stack of money bags. When you finish the game in the NES version, the game starts over... though Samus retains all her power-ups, except for Energy Tanks and Missiles, for this second play-through. This is not the case in the FDS version, where you simply restart the game again with no power-ups.

Armorless Samus


If you finish the game under three hours in the NES version, you will start the second play-through with an armor-less Samus. The FDS version does not have this "bonus feature."

HUD
The digits for energy and missiles have a blue dropshadow in the FDS version. This minor difference is also seen on the timer that appears in the escape sequence.

Mother Brain
In the FDS version, a much larger part of the tank is destroyed while fighting Mother Brain. In the NES version, it was changed so that the tank only shatters near Mother Brain's vulnerable area.

Ending
The color palette of the text in the ending message was changed from blue to yellow for the NES version. "IN THE SPACE" was also changed to "IN SPACE", but the Engrish is still hilariously bad.

End Credits
The credits' blue palette was changed to cyan and some odd grammar was corrected in the NES version.

MAIN PROGRAMMED BY was changed to MAIN PROGRAMMERS.

TOHRYU MAKO and BENKEI were replaced with T.NARIHIRO, who converted the game to the NES cartridge format.

CHIEF DIRECTED BY was changed to CHIEF DIRECTOR.

The End went from a dark blue to the same cyan used by the rest of the credits in the NES version, and the PUSH START BUTTON text was removed.

Other Differences

 * Due to having extra memory provided by the FDS RAM adapter, the FDS version features enemies that behaves in a more random fashion. For example, the "Squeepts" in Norfair can change their height in between jumps (low, middle or high) but the NES version will restrict the state of the enemy so that it can only jump at one set height (low or high) that will be redetermined only when the enemy data leaves memory. This removed the unpredictability of certain enemies in the NES version.


 * Other examples of this is noticeable with the "Dragons" in Norfair which in the FDS version can fire either one, two, or three fireballs randomly. In the NES version they either spit three fireballs or strangely enough none at all (most likely a bug of some sort, the animation is still there). Another case is Ridley's fireball attacks which in the NES version either feature the slow traveling ones or the long traveling ones. In the FDS version, Ridley spits out both types of fireballs randomly which makes him slightly more challenging. The "Side Hoppers" and "Dessgeegas" random behaviour was also affected in a similar way.


 * The indestructible "enemy" in Norfair called "Polyps" behave differently between versions. In the NES version of the game the small objects are either fired left or right in an arc, in the original FDS version, they are fired erratically and randomly on both sides, making them a much tougher obstacle.


 * As the game is being stored on disk instead of cartridge, the Japanese version has short loading times when you go between the 5 areas in the game, and requires you to flip the disk occasionally.


 * The FDS version has far less slowdown than the NES version. This is most noticeable in boss battles, as well as much of "Tourian", the last area in the game.

Music
The compositions in the Japanese version are much richer in many tracks, due to utilizing the system's wavetable sound channel.
 * Title:


 * Samus Appearance:


 * Item Obtainment:


 * Escape:

The Escape Theme is a little shorter in the FDS version; an extended section was added to the track in the NES version, a section that sounds similar to what the composer wrote for Kid Icarus.
 * Ending:

Sound Effects
The FDS version also utilizes the system's wavetable sound channel for several sound effects:
 * The bosses Kraid, Ridley and Mother Brain all sound different when they take damage; this is also the case with Metroids and other larger enemies.
 * The alarm that is heard when the time bomb is activated is different.
 * The sound of doors opening and closing is different.
 * The sound effect for the Ice Beam and Wave Beam is different.
 * The sound effect for the Screw Attack is different.
 * The sound effect when Samus dies is different.
 * The sound when Samus takes damage is different and uses the same audio as Link in the FDS version of Zelda.
 * The warning signal when Samus's energy is low is different.

Other Audio Differences
A few audio refinements were made to the NES version, such as:
 * In the NES version there's a sound effect when the Dragons spit their fireballs, in the FDS version there was no sound effect.
 * In the NES version there's a sound effect when you shoot the statues of Kraid and Ridley when you have beaten them, in the FDS version there was no sound.

Revisional Differences
Metroid was re-released on the GBA and for other systems later on, including as an unlockable in both Metroid Prime and Metroid Zero Mission. While the Japanese version of Metroid Prime included the FDS version as an unlockable, it was the NES version of Metroid that was used as an unlockable in the Japanese version of Metroid: Zero Mission. A port of the FDS version was released separately as Famicom Mini Vol. 23: Metroid.

Metroid: Zero Mission

 * The title screen had some text changes. The coloring of the background has also been altered for whatever reason, possibly a palette issue.


 * All instances of PASS WORD were changed to PASSWORD, including the password entry screen and being given a password after dying.