This game is unbelievable for an indie dev to create for free. Production values are through the roof. It plays like Zero Mission on the GBA and arguably does a better job of remaking the classic than the official 3DS Samus Returns game.
I’m playing on PC but there is also an Android APK if you search for it.
It is amazing! A couple years ago I played through the Metroid series (not every game original/remake counted) and it was one of my top games. It did have one issue IMO, once you get the screw attack there is an expectation that you are familiar with how to use it, which as a new player, took me a very long time to get past. But other than that I loved my time with it & didn’t have any complaints!