Said to be one of the best games ever, it was almost never got made. It came close to being shut down twice during it’s production.
It was the biggest game Nintendo made, be delivered on a 24megabit cartridge. R&D1 [the makers] filled it with great atmosphere, intense playability, expansive non-linear maps, haunting music, numerous memorable moments, hidden areas including powerful & diverse weapons & enemies.
It was more than just a platformer, offering up new things like beneficial backtracking, a dynamic weapons upgrade system & an automated mapping system. For example Castle Vania (Symphony of the Night) simply wouldn’t exist without borrowing these things from it’s Metroid heritage..
The female protagonist [Samus] was based on Kim Basinger & the name “Metroid” was a combination of the words metro & android.