Metroid Fusion (played on Game Boy Advanced Emulator) - This deservedly criticized for being too linear, which feels like something of a betrayal, even if the second one was linear too and I liked that one. Also you read a bunch of text and the game really holds you and and tells you where to go and there's a dumb "emotional" component to the story that aims for resonance and just falls flat on its face. The music isn't memorable either.
So does that mean it sucks? No, it's actually still a really good game. The gameplay is fun, the bosses are much better than in the previous games (except the one returning boss, Ridley. That fight is mindless in all the games except Super Metroid), and if the exploration doesn't approach the previous game at least the atmosphere is still cool and creepy.
This might not be as replayable as the first and third game though. The bosses were challenging but I beat it with only 57% of the items and didn't wish that it was any harder.
Zero Mission (also played on GBA emulator) - This is a remake of the first game, but the gameplay is more of a compromise between Super Metroid and Fusion. There's more handholding than Super Metorid (let alone the original) but the opportunity to break the obvious sequence. It looks better than fusion, it's certainly more accessible than the original game that it remakes, and Super Metorid fans will enjoy it even if they didn't like Fusion.
That said, I do have some complaints. Some people praised the atmosphere but to me it's a huge misfire. If this was my first Metorid game I wouldn't have had a problem with it, but I think the sense of isolation and creepiness is gone. This one feels like it's supposed to be a more upbeat adventure.
It added some mini-bosses and some of them were pretty good, but I thought that the bosses were lame. Craid is harder than he was in Super but otherwise the same. Ridley is one of those fights where you just throw yourself at the boss firing wildly and you'll probably survive. Mother Brain is like the original but more frustrating.
But oh wait, there's more left after Mother Brain! The Space Pirates shoot you down after the escape and you crash without your suit. It becomes a stealth game until you find an even better suit, kick everyone's ass, and then fight Mecha Ridley, who is tricky if you have trouble timing your attacks and easy if you don't. Some people hated the stealth sequence but I loved it and thought that this last portion was the most fun part of the game (except one bit, but we'll get to that).
One more issue: there are three difficulty settings, but you have to beat the game once to unlock the hard difficulty (it also unlocks a version of the NES game, although I think the graphics look off). I would rather have played it on hard first, since I thought the game was too easy on normal. That said, there is one part that I thought was too hard. At the end of the second and final timed escape sequence you have to fight two very tough Space Pirates. I didn't even remember having to do this on normal, but on hard it's some Castlevania-Grim Reaper level shit, complete with a cheap easy way to beat it using an exploit that I learned on youtube after beating it the hard way on my own.
Another Metroid II Remake (AM2R) - This is an unlicensed game made independently and given away for free. It came out in 2016 and was promptly served a cease and desist order from Nintendo.
Well, Nintendo must have been jealous, because this is hands down the best 2D Metroid game, after Super Metorid (and to be clear, I never played any of the 3D games). I haven't enjoyed a game this much in years. It's got terrific atmosphere and fun, challenging bosses. Without beating it and unlocking the alternate versions that I haven't played yet it does have the linear structure of the original Metroid II, but the individual sections are so cavernous and well designed that it recaptures the sense of exploration that Fusion lacked.
It also fixes the biggest complains about the original M2. There is a map, although it only fills in as you explore, there are no map computers. The different areas all have distinct looks, and whereas people complained that your sprite was too big in the original, Samus has never taken up less of the screen than she does here, and the game uses this space really well.
There's also some new story, but it appears in logs that you can access through a menu, so that part of the game is there if you care about it but can be ignored if you don't.
I also think that, like the original M2, it's easier to find most of the missile and bomb reserves in this game than it is in some of the others.
I only have a few complains, and they're not that significant. They did a good job designing the first two metroid forms the the two higher forms are just tedious and annoying to fight.
Also, the game builds up some mystery around certain locations you pass throughout the game that you can't access and then provides a cool way to shortcut back to them toward the end, but it turns out to be much ado about very little.
I appreciated that although there are some alternate versions that you unlock when you beat it, allowing you to play a version that allows greater sequence breaking and a version with randomly placed items (although I haven't tried these), I was able to play the regular hard mode without having to beat it on normal first. I thought the difficulty was just right. Nothing was infuriating like that crap at the end of Zero Mission.
I haven't played the official release, Samus Returns, because I don't have 3DS. Just an SNES and a computer.