I personally enjoy playing "Environmental Station Alpha" (or "ESA" for short) more than any Metroid game, but it'll all come down to personal preference. This is a straight up Metroid clone, and it's not shameless about it- but at the same time, it clearly tries to ascend past that into something new entirely. The Metroid trappings are typical and what you'd expect, and your enjoyment of the game will come from whether or not you jive with the additional stuff added on top that make ESA unique and stand out on it's own.
While going through the first half of the game, you'll see obviously inspired areas and fight bosses that seem uncanny to things you fought in
Super Metroid. The powerups are basic, but diverge a lot from the typical Metroid game: a grappling hook and aerial dash boosts are your main form of movement. The level design is also extremely good at slowly turning up the difficulty on using these, and by the end you'll be performing chain dashes over instant kill spikes without hesitating or batting an eye. While some sections will make you want to yell at your screen in frustration, I never felt like those sullied my opinion of the game as they were fairly infrequent.
But during the second half of the game and beyond, things really open up. You start to find that the station is a lot less linear than most Metroid games, and that you can do content so out of order that you almost get lost! Computers that you can find point you to a common goal, but other than that (and a few map related hints) you are mostly on your own. There were some bosses that I ended up killing in under 10 seconds, and realized that I was supposed to fight them much, much earlier than I actually got around to (and of course, vice versa... I was definitely stumped on a few sections that gave me powerups way before I was meant to have them!).
What shines most to me though, is the
Postgame; while it feels really hard to say a game is great because of the content after you've beaten it, that is definitely at least partially true for ESA. While exploring, you'll find weird secrets that seem to point to nothing found in the actual game. "Pillars" will activate, you'll find alien text that you have to translate into English, and you'll come across seemingly empty rooms with strange sigils all over the walls. But while some of this stuff seeps into the main game for most players to encounter, to find most of it you really have to dig deep into the labyrinthian station and abuse many secret finding techniques. What results is a quest to get four additional endings (for comparison, the base game only has one) that is nearly as long as the original game. It's definitely full of "bring a pen and paper" puzzles, and there are some really dumb developer logic parts- but overall this insane jump from a classic Metroid game into a weird riddle solving experience is really what makes ESA stand out for me. It's no surprise that the lead developer went on to make "
Baba Is You", since that game is just as brilliant in a lot of the same ways.