- level one is decently long, but i didn't see a midway point
- level two's enemy variation seems non-existent
- yellow switch is good, though i have to ask why there are bushes indoors
- so far i see an over use of coins, in fact i already have 9 lives, i haven't died and two of them came from actual 1-up mushrooms
- spiny falls through message block at the beginning of level two, shift it over to the right
- there is a glitchy dino rhino where it partially clips into two question blocks, you may want to fix that
- major problem, collecting the midway point forces a reset because you didn't make the pipe enterable
- move the coins that lead the player down a blind jump over a tile or two to the left as it can lead to an unfair death by dino rhino
- the yoshi coin with the turnblocks can make the player get stuck if they are small, this didn't happen to me but it's entirely possible
- level three everything looks faded, while this isn't a problem i think it looks a little dull
- the rope seems unnecessary
- the palette style changes halfway through from an underway-esque faded palette to a nighttime dark palette
- i do like the way every level ends in a "this is what's next" feel, that's really neat
- in level 4 a super koopa runs a little while off the edge before jumping and flying
- level 2 world 2 you forgot to make layer 3 have priority over all others
- forced spinjump section, which also seems to be filler
- "where ghosts dwell" the bonus room scrolls to the right when it obviously shouldn't
- big boo is missing half of its face and mario is invisible
- the level is basically a giant confusing item babysitting fest
- "wendy walkway" is extremely claustrophobic at the beginning
- why are there coins in a boss fight
- the tone of the level palette-wise changes about 4 or 5 times
- wendy battle is insane, while this isn't a problem it was a hassle to beat her without savestates
- cannot enter monochrome cave, i assume this is the end of the demo
- overall you should more thoroughly test your levels for errors and bugs and oversights, as these plagued the hack