Who would ever believe that, behind that characteristic space battlesuit armed to annihilate monstrous alien creatures, was hiding one of the most successful female protagonists in the history of video games (Samus Aran) who would lead the famous Metroid franchise to achieve unimaginable success, and who would conquer several decades of history, thus pleasing an audience of all ages and nationalities. Next, I will introduce some secrets and curiosities that accompanied the history of this classic video game: 1. A Metroid was planned for Nintendo 64 but, finally, the project was rejected. 2. Samus Aran’s physical appearance is based on actress Kim Basinger. 3. In Bayonetta 1 and 2, we 1 managed to find the Galactic Bounty Hunter, which gives us a new suit and the new cannon for Samus Aran’s Power Suit. 4. The NES version of Metroid is the only one in which we can’t see the spaceship in which Samus travels. 5. On the original Metroid cartridge board there is a space where a battery slot was to be located to save the game. It was finally removed due to the high cost involved. 6. The Super Metroid map is based on a map design made for another game. 7. Metroid Prime 2: Echoes, was the first title in the saga to feature multiplayer gameplay. 8. All the games in the saga have a countdown, except Metroid Il. 9. In Super Mario RPG, Samus had a small cameo while appeared lying on a bed. 10. Super Metroid was the first cartridge with 24 MB capacity for SNES. 11. In the first Metroid manual, Samus is referred to as if she were a man, but this is not a mistake: it is done on purpose, so as not to reveal that she is a woman. 12. The famous Dr. House appears in episode 3 of the first season playing Metroid: Zero Mission on a GB Advance. 13. Nintendo re-released Metroid in the U.S. as part of a lineup of classic games, changing only the cover art. All this happened shortly before launching SNES. 14. The original Metroid for NES has five different endings that change depending on the costume, items, and the time it takes you to finish it. 15. SR388 is the name of the Metroids’ planet and comes from the name of Yamaha motorcycle engine, the SR400. 16. In Japan, the ability to become a Morph Ball is called “Maru-Mari”, which means “spherical ball”. 17. Samus’ life counter starts at 99 in all titles of the saga except in the NES version of Metroid, where it starts at 30.18. In Kid Icarus, also created by Intelligent Systems, metroids appear on some levels. 19. Metroid II: Return of Samus, is the only game of the saga in which you can see the evolution of the Metroids since their birth. 19. Metroid: Other M, is the first title of the saga in which we finally hear Samus’ voice, which until then had remained silent.