Nice demo overall, great art and nice sound, gameplay needs tightening up, in my opinion. Environmental threats are not apparent, even the red spikes are too muted to be noticed sometimes. Walljump is really weak (it's even in the gif on this page) and you can grab ledges for some reason, but the window for it is so tiny it happens by accident rather than when you want it too.
The snake hitboxes are really weird, i think the tongue can kill you, even though you should be safe when standing on the platform. The breaking floor timing was too tight for my taste, you can add just a little bit more for grampa videogame players like me.
Oh, and the starting menu shook like crazy for me, not sure why, since the gif on the page is not showing any of that.
Oh and i had to jump over the "NEW GAME" tile, since it blocked walking. Main Menu is working real weird for me, huh.