Just finished the demo, and well... I see what you meant by "really awesome stuff". That end-of-demo boss battle was seriously one of the most interesting ones I have seen in quite a while. In fact, the whole hack is definitely up there when it comes to creativity; I can't recall any other hack changing the gameplay mechanics to this extent. Sure, there may have been some slight technical problems here and there (I don't blame you too much, though; I can only imagine how annoying placing invisible helper tiles in every corner must be...), but it's still definitely one of the most fun hacks I have played recently.
I do have one nitpick when it comes to the game mechanics, though; it feels kind of strange how Saph can kill Chucks by shell slamming into them, but gets hurt if he is sliding instead. In fact, is there any reason you couldn't disable sliding down hills entirely and just keep the shell slam? After all, they serve almost completely the same purpose.
On another note, how many worlds are you planning for this to be?
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