I lack the ability to comprehend Shine's work ethic. As a Metroid fan myself since childhood, to say that this mod is more than I could have hoped for, let alone dreamed of, is a vast understatement. I just finished it last night at 100%, and I still can't get over how many little things you put into this. Though, I suppose I shouldn't surprised when this is coming from the maker of SMS Reborn. It's not perfect obviously, as nothing in life is, but it sure is close.
My two biggest critiques are:
1) The arm cannon fires lower than the cross-hair in 1stP mode. This is probably the most egregious issue, and one that I would STRONGLY urge you to fix whenever you can.
At first I wasn't sure if this was just a hold-over from Ringslinger modes and I just wasn't used to it, but as I watched some other people play, they too also commented on the targeting discrepancy, so I know i'm not the only one who finds this annoying. It also often makes it finnicky to fire at targets on the ground in front of you, as you shots will often just hit right into the ground. Obviously you can just say "lol just remember to aim above them its ez", but it'd be nice to not have to remember to do that all the time.
^^^ Fix this at your earliest convenience, cuz I have a feeling that doing so will greatly boost the QoL of this mod.
2) Egg Guard's hyper mode ability sometimes makes traversing CEZ 2 a literal kaizo-esque NIGHTMARE.
And I know why this is happening, too: It's a combination of A) the unique level design of CEZ 2, and B) the fact that enemy LoS calculations don't take the Z axis into account. What this all MEANS (as i'm sure you recognize, since I imagine you must have play tested all levels extensively during development) is that: If you hit a spring while high above in a certain room, and there are Egg Guards on the floor of that room, they will teleport to you, and due to your momentum, you more than likely wont have a chance to kill them before they kill all of your aerial momentum, condemning you to plummet back down to the bottom of the room.
As far as how to fix this WITHOUT nerfing the Egg Guard? Honestly, all I can think of is to literally just move Egg Guards away from rooms that have vertical or diagonal springs. Cuz the problem isn't necessarily the ability itself: It's the level design of CEZ 2 that causes this phenemona to happen, along with the lack of Z-axis checking in LoS calcs.
Sorry about the lag, though! Software mode in particular can be a big offender. Right now enemy rolling is also enabled, which lags like crazy on 2.2.8 but not 2.2.9 and beyond. Making different code to be cross-compatible with SRB2's different versions and renders is a pain. I've made a temporary fix for it in v1.1.
Though you kinda NEED the beam combos and fancy powerbomb explosions to take down the final boss. It's designed to only take 2~3 minutes, but that can easily become 10+ if you mainly use the basic beams.