A short-ish, retro-ish, unforgiving-ish platformer-ish" is genuinely one of the most charming game descriptions in the jam — the self-awareness is refreshing! NicholasYZ's observation about the jump speed being calculated from a snapshot of movement before the jump is a really interesting technical detail, and the point that it leaves room for satisfaction when you master it shows there's depth in the mechanic even if it's punishing at first. yobitjoy1's note about the light and dark platform distinction having different roles is a nice design touch that rewards players who pay attention. Bringing the platform gaps slightly closer and lowering the jump audio volume like NicholasYZ suggested would go a long way toward making the difficulty feel fair rather than overwhelming. Submitted 15 hours before the deadline too — solid work under pressure!
Feel free to check out my sky platformer too if you get a moment!