The level layouts seem coherent and glitch-free, though, and to me, only three things matter in a hack - It's fun, it's consistent, and it's original. You definitely have an idea of what you're doing. I'm also happy that you made this a fairly long game (96 exits) and that alone shows you dedicated a lot of time to this hack.
I can't really judge level design by these screenshots, so I'm going to play the game tomorrow to get a better idea. I hope you will have some puzzles and hide things like dragon coins for challenge rather than try to make it difficult by adding jumps with low ceilings+wide gaps and too many enemies in one place, but it looks pretty well-controlled, so I have faith in the idea that you didn't make that mistake. I do like the fact that you used the creating/eating block train gizmo, though, because I rarely see those. *downloads and patches, then waits until morning*
Now, onto the bad news... It's already been pointed out that there are some palette issues, but I'm going to elaborate on it and a few other things. I have a lot of things to say, but keep in mind that in spite of all these negative things, my tone is peaceful
, and I'm only trying to help, and not flame. I might sound a little picky, though, since I'm trying to point out everything. D:
-In the first screenshot, the Marble Zone GFX are glaringly orange. I'd recommend something easier on the eyes, such as a bluish or greenish gray.
-In the second screenshot, the classic piranha plant's stem palette is still red, and most people don't like that, so you should use the patch to change it to green. Also, the wooden SMB3 block seems a little bright.
-The desert floor and pyramids in the third screenshot could be dimmed so that it looks like it's nighttime (and maybe make the pyramid a little darker than the sand.)
-In the fourth picture, the green question mark blocks don't look too good at the bottom, and the Goomba is bright/could use an outline to fit in more with the SMB3 style.
-In the 6th one, the "used" block's outline seems strange as white - I'd recommend dark brown or black, and you may want to outline the spikes to make 100% sure the player knows they're in the FG and WILL hurt if touched.
-The background in the 8th screenshot... The yellow background needs to go, but it's cool to see layer 3 mist used with the airship. For the BG color, I don't know if you want night or day, but some shade of blue would be appropriate.
-In the 12th screenshot, you may want to dim the BG clouds just enough so that it doesn't seem like the fence is chopped off at one point. It's impossible to see the snow on it.
-The 13th screenshot's foreground seems to be put together strangely. My main issue here is with the wide pillar being in the left wall and the way that there's a thin pillar between huge chunks of pillar toward the right side.
-The 14th screenshot's FG could also be darkened a little to better suit the night sky.
-The orange bridge in the title screen is screaming - but since it looks like a steel bar to me, I'd say make it gray.
-In the 21st screenshot, the mushroom platform and the wooden objects' styles conflict, so you could either add a darker outline to the mushrooms or lighten the outlines of the wooden objects to make them go together better.
-In the 23rd screenshot, the small ice blocks could be tweaked just a wee bit to not be so bright.
-The sand ground in the 24th screenshot should be made more brown - or is it sand? Hmm... Either way, orange is generally a color you don't want to be dominant unless it's a sunset because of how strong it is and how it doesn't seem to work with many things.
-25th screenshot - I don't like the black on the stripes of the hills. A dark green would be much better.
-For the 26th screenshot, I think you should copy the foreground palette from the 4th screenshot's level, then darken it a little.
-28th screenshot - I can tell what you're trying to do here - a frozen ship, right? I'd go with a bluish gray or a pale brown... either or, but not a combination of them.
-In the last screenshot, again, the foreground is too bright for a night setting. Dim the FG palettes a little, and change the sand to a more brownish color.
In short, lots of things are a little too bright in some spots, and overuse of yellow/orange hurt people's eyes easily.
I'm sure you're aware that in a few screenshots, you have issues with the status bar's palette. There is a simple but somewhat time-consuming way to remedy this - transfer the colors from palette 0 to palette 3, 4, 5, 6, or 7 and alter the Map16 tiles the BG uses so that they use the new palette line you've selected. If you don't have any objects that use a certain palette, then that's probably your best bet for moving the BG palettes to. Then, from a level with a normal palette, copy palette 0's (or 1's) colors back onto the level with the status bar that needs to be fixed, putting the colors in the same place.
Regardless, though - you should remember that ROM hacking is a hobby, and it should be fun for you. You clearly put a lot of effort this hack so far, and I want to see it live up to its full potential. I hope this advice and that of other people can help you make a true final version, better than the last, but take your time with it - if it ever seems like work, then there's something wrong.
Again, I will play the game soon, and when I finish, I'll try to give more advice and a full review.
Edit - The levels were mostly really fun and felt like retro-style Mario. I found a minor bug with Yoshi's tongue in the first Star World level. I hope my review is useful... check your hack page. Yeah, it's a long review. :|
Just look above you...
If it's something that can be stopped, then just try to stop it!