yeh my game had that problem as wel at certain points (and will have that problem again)
"underwater - maneuvers" at the start has water with an immediate saw at the top off-screen. luckily at the start so not very frustrating, but still.
"wilds - vines" pretty much every point where you have to leave a grapple-thing is a leap of faith.
"wilds - double use" same leap of faith problem. that saw just before the end is very cheeky. i would actually applaud that if it weren't for the leap of faith grapples i had to do before
"wilds - freeform swinging" this is the last level i cleared. every scenario waiting off-screen is preceeded by leap of faith grappling and you have to keep a certain amount of momentum going otherwise you're dead anyway. questions i have while swinging that first grapple-thing: am i going fast enough? when am i supposed to let go? what angle am i supposed to be at? all unknowns.
the rail grinding has kinda the same problem where i kinda need to know to charge before i see the need to charge, but i didn't finish any of those levels.
possible solutions: smaller swinging circles(this might cause problems with release timing), have the camera zoomed out even further beyond, make the mandatory speeds you have to achieve less (just make me be able to scrape by with 1 star), have a "look at level" function like celeste has so you're not surprised by cheeky little saws. with all the trial and error i'd still say this was a fun demo for the most part.
last thing. could you make it so you can fart stars while swinging? that would be sweet