Metroid was released on August 06, 1986 in Japan for 2600 Yen.
The Morph Ball was partly invented out of convenience. At the time, it was much easier to animate a ball rolling through narrow passages than a computer figure crawling on all fours.
The second boss of the game, Ridley, was named in honor of Ridley Scott, the director of Alien (1979).
When it was first released, Metroid held a secret about its armor-clad protagonist, Samus Aran. When the game was beaten in under 2 hours, the player was presented with an image of Samus, whose armor then disappeared, revealing that the character is actually a woman. Samus Aran has since gone on to be recognized as one of the earliest and most famous female video game protagonists ever. The decision to make the mysterious bounty hunter Samus Aran a woman was made halfway through the development process. Samus was initially going to be a male, but it was changed because it would be a cool surprise for the gamers.
Some gamers stumbled upon a glitch in the game, where it was possible to jump through a door and get stuck in a wall. From there, it would be possible to jump through walls into normally inaccessible areas with strange layouts. This gave rise to a popular video legend of the 'Secret Worlds' in Metroid, which were only accessible to clever players. Years later, it was revealed that these secret levels were actually unused map data that were supposed to be outside the playable area. There was never any intention to make these areas accessible in any way.
Cameos in other Samus Aran Nintendo titles :
1. Kid Icarus (1986, NES) a enemy creature named Komayto , meaning "little Metroid" a resembling of Metroid creature.
2. Famicom Wars (1988, Famicom) (Unreleased outside Japan; The Orange Star commander on Donut Island is called Samasuun, and her face on the result screen is Samus's mask).
3. Nintendo's Tetris (1989, NES) (Cameo, appears playing the upright bass after the player wins a B-type game of level at least 9 and height at least 2).
4. F-1 Race (1990, Game Boy) (Cameo, appears cheering before Course 7)
5. Galactic Pinball (Virtual Boy) (Cameo, her ship appears in a minigame).
6. Super Mario RPG - Legend of the Seven Stars (1996, SNES) (Cameo, after Mario's party defeats Yaridovich, he may her find sleeping, until Mario travels to Land's End, and a Samus figurine appears in the toy box of Booster's Room).
7. Kirby Super Star (1996, SNES) (Cameo, when Kirby uses his rock defense he can become a Samus statue. Also, the Screw Attack icon (called the Screwball) is a treasure in the Great Cave Offensive segment of the game).
8. Kirby's Dream Land 3 (1997, SNES) (Cameo, appears after level 5-2, which also contains six Metroids).
9. Super Smash Bros. (1999, N64) (Playable character).
10. Super Smash Bros. Melee (2001, GameCube) (Playable character).
11. WarioWare, Inc. - Mega Microgames (2003, Game Boy Advance) (Contains a microgame based on NES Metroid).
12. WarioWare, Inc. - Mega Party Games (2004, Nintendo GameCube) (Contains the same Metroid microgame from Mega Microgames).
13. WarioWare - Touched! (2005, Nintendo DS) (Contains a microgame based on NES Metroid).
14. WarioWare - Twisted! (2005, Game Boy Advance) (Contains two microgames based on NES Metroid).
15. Animal Crossing - Wild World (2006, Nintendo DS) (Gulliver, the seagull, references Samus saying 'Tell me, have you ever heard of the bounty hunter that can turn into a ball?'. Also you can get a 1x1 item that is a Metroid in a case, when you touch it it glows and plays a small clip of Metroid music).
16. Geist (2005) (Samus' helmet is seen in a women’s locker room).
17. Tetris DS (2006, Nintendo DS) (Metroid-based course, Catch; in the title screen, Samus shoots some tetrominoes; A difficulty level on Standard mode is Metroid Themed, with Samus to the right, and clips of the original Metroid playing on the top screen).
18. WarioWare - Smooth Moves (2007, Wii) (Contains a microgame based on Metroid Prime 2).
19. Super Smash Bros. Brawl (2007, Wii) (Playable character, Zero Suit Samus is also a playable character).
20. Dead or Alive: Dimensions (2011, Nintendo 3DS)(included a stage based on Metroid: Other M in with Ridley, a stage hazard he appearing attacking the fighters, while Samus appears at the end of the encounter to help them.
21. A Multiplayer shooter game Nintendo Land (2012, for Wii U, called 'Metroid Blast' based on the Metroid Universe.
22. Fatal Frame IV: Mask of the Lunar Eclipse (2008, Wii) a Unlockable Costume Zero Suit Samus.
23. AR Games (2011, Nintendo 3DS) (AR cards, A "3D augmented reality" include a card of samus featuring a 3d model of samus in a "Other M style"
24. Dynasty Warriors Vs. (2012, Nintendo 3DS) an Unlockable Costume Zero Suit Samus.
25. Kid Icarus: Uprising (2012, Nintendo 3DS) The Komayto creature reappears and feature a AR card Komayto!
26. Tekken Tag Tournament 2 (2012, Nintendo Wii U) an Unlockable Costume Zero Suit Samus.
27. Donkey Kong Country - Tropical Freeze (2014, Nintendo Wii U) In the level Busted Bayou, Samus's gunship can be seen lying semi-hidden in the trees in the background.
28. NES Remix 2(2014, Nintendo Wii U) Contains a series of challenges mini game based on the first Metroid game.
Known export releases:
"Metroid [Model NES-MT-USA]
"Metroid [Model NES-MT-EEC]
"Metroid [Model NES-MT-ESP]
"Metroid [Model NES-MT-FRA]
"Metroid [Model NES-MT-NOE]