As you may have heard, it's Metroid's 30th birthday today! While Nintendo may have killed off the franchise years ago, the developers of AM2R have released the first full version of the game to celebrate.
If you've never heard of the project, AM2R is a fan-made remaster of Metroid II: Return of Samus that has been in development for a VERY long time. The original game has aged pretty poorly and lacks a lot of things that became welcomed staples of the series, so AM2R aims to bring it up to modern standards. Maps, status screens, better controls, even log entries that didn't become a thing until the Prime games have all been added to make it less "it's 1991 and this is the only game you own so we made it disgustingly hard to last you a long time" and "you'd better have a subscription to Nintendo Power or you'll be lost forever." It borrows some Metroid: Zero Mission assets, and adds a lot of its own visual and musical content as well. It even has native controller support!
You can visit the AM2R blog here.Edit: It appears the post containing the official download, as well as the files themselves, have been removed. There has been no word from the developer about this, but all the download links show that they were taken down by DMCA notices from Nintendo. Unfortunately you'll have to seek it out elsewhere.
Edit 2: The developer has received an official DMCA takedown notice from Nintendo, and has therefore shut down development on the game. You can still find the preexisting copies floating around the internet, but there's a good chance this is all we'll be getting.