Quite a neat hack you've got there. It has that certain "JUMP" feeling, I think you were going for, with lots of interesting setups.
I have to admit, I dind't play the hack savestate-less, although I'm pretty sure it is very doable (which I think you were going for).
Starting of with "Falling for you": Probably my least favorite level out of the bunch, mainly due to the long waiting times on the "long-lasting-timed-lifts" completely interrupting the fast-action of the level. Try making the rides on these long-lasting-lifts a little more exiciting. However especially the jumps over/under the piranha plants were very enjoyable.
"Draft day": Decent level overall, with some really unique sections although a little too much on the football/football chuck side of thigs, for my taste. The setup, where you had to shoot the chuck with the fireflower stood out the most.
"Spiky balls": First of great level name, very accurate xD. Overall rather enjoyable with the first half maybe being too much on the short and easy side. The very last jumps were the most memorable ones for me.
"Slip slidin' away": I really love this level, contender for my favorite level out of these. These quick slide jumps are super fun.
"Spring 'n things": While I really do hate these wall springs (they are way to finicky and hard to control) the level was still very entertaining for me. Just overall excellent enemy placement and interesting setups, only these wide jumps (e.g. very last jump) are quite annoying to make.
"Dino-rhino ridge": The beginng and end of the level are well designed. Just the cave section feels a little slow and sameish to me.
Hope at least parts of these quick thoughts are useful. Overall had lots of fun playing through the demo and I'll look foward to seeing more progress on the hack
Check out my new hack thread: