>>717828001
V1.0 had enemies hit ridiculously hard. V1.1 nerfed damage output in general in the earlier areas (pre-Varia), but some things still drain you fast. Sector-6 when you reach it, is absolutely a difficulty wall though, and the difficulty kinda remains higher from there on. Final area is just bullshit in general, no mistakes allowed w/ tight platforming. Game assumes you know how to walljump (and Fusion limitation of being unable to walljump repeatedly off the same wall), and grapple with high gravity, that's about it that I recall the main path expecting. Some of the item pickup rooms later require some speedrunner tricks, but they're not mandatory to beat the game.
V1.2 added an Easy difficulty, which halves damage taken (you are still receiving more damage than an official Metroid game) and adjusts the AI of certain enemies that fuck your shit up, including the aforementioned difficulty wall section.