So far I completed world 1 and I can tell that this is a pretty good start for a hack, the difficulty is perfect and your level design is quite nintendo-ish, which is for me a good thing. The first level was quite flat, but had some nicely hidden secrets, just like the first part of the second level. The second half (underwater) was way to short and a little bit uncreative. The third level has a really good gimmick, but some enemies are no harm for the player at all. The next level was my favorite one, with a lot of tricky sections and nice ideas. Iggy's castle kinda' felt like a slightly edited original level, especially the second half with the layer 3 smashers.
In conclusion it's a nice start, but some levels are too flat or feel like blatant edits, btw I also recommend you to post some screenshots.
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