You put together a cool game!! Interesting redo of Mario :D
Loved the fast paced movement, and catchy music, very dynamic and smooth controls ;) The pixel style works good, somebody chose some good color combinations and nuances! Also loved the parallax at the beginning, do it more next time ;) Funny comments on the "actors" hehe
"Why are there invisible colliders (sometimes on grass sprites) and why does the character sometimes land inside the green grass platform?" <- nevermind, I saw the credits :) Don't take this personally, but that jump sound is so overused in many retro games, including my "LINK" too :( Tune it to something more original (I raised the pitch way up, you tune it more!), even if you want to give the nostalgic feeling, be unique, with unique sounds!
Was there supposed to be some mechanic with touching the dark ones? Besides the screen shortly flashing dark?