Talking in this thread made that Metroid itch come back so I started playing a ROM hack called X-Fusion. It actualy got brought up earlier in the thread but it wasn't talked about in too much detail.

People made pretty big deal when it came out so I thought I'd finally give it a shot. Boy lemme tell ya, my play time is only 1:09 but this is already the most impressive Metroid hack I've seen from a technical perspective, and I've played my fair share of Metroid hacks both GBA and Super.
Just gonna list off a bunch of cool shit the mod has shown so far
-4 bosses so far despite only being an hour in. 3 of them are revamped fights from Fusion and Super with new attacks and arenas to make them more challenging and 1 totally unique boss that I loved
-B.O.X. is a controlable mech you use to get past lava, thought a bit jank, I thought it was really cool. You even use him during a boss fight which I found really fun
-A dialogue system, though your choices don't seem to matter it is neat to see.
-And my favourite so far, you can change the water levels in sector AQA. The area has been redesigned around this turning the whole area into a sort of puzzle. Think the water temple from OoT
As far as level design, it is still very Fusion. You are funneled into specific areas and Adam gives you objective markers. So if you hate Fusion you'll likely hate this. I do find it fun to see Fusion's map remade in this way. Areas are recognizable and even specific rooms look exactly like their Fusion counter parts but they're kinda mixed and matched. It reminds me of that "Mario 64 made from memory" mod from a few years ago, but this mixing up of the order and areas is clearly intentional. I also like the way SA-X is handled. It is made clear that there are several SA-X right from the start and you can run into them while exploring. They only spawn in specific rooms and a unique theme will start playing when you enter a room with a SA-X. So when you go through a door and hear that music your options are either turn around or get ready to juke, because if they see you they will chase you through the whole area. And they deal mutiple energy tanks per hit which in the early game is a 1 hit kill.
There's also a bunch of dificulties to choose from.

I'm currently playing through the game on normal. Samus' HP and the damage output of enemies feels on par with Zero Mission's hard mode. Though I think it's harder than Zero Mission's hard mode mainly because the bosses are lot more challenging and dynamic than Zero Mission's. I made another file on hard to see how much of a difference there was, this is when the game really blew me away. Not only is enemy damage increased but the
map and areas are changed too. The start of the game on normal goes >initial "fake" boss fight (think first Ridley fight in SM) >escape sequence >small area with minor enemies and save station >first real boss. On the hard it goes >"fake" boss >a
different escape sequence with more challenging platforming that has required wall jumps and a SA-X starts chasing you in the second half >one small room with no save station or minor enemies to get health from >first real boss. If you die on the first boss on hard you have to start from the
very begining.
All around, I'm really liking it so far and I'll probably make another post once I'm done with the mod.