4-6: Looks interesting, though that Blooper looks very difficult to get past. I actually like the background, though I wouldn't say no to a Layer 3 effect either behind it or in front of the foreground.
4-7:
Pansers do not work that way! Er, questionable custom sprite coding accuracy aside, the level seems decent enough (you'd think more people would use Pansers, especially in jungle levels), and the background gradient is pretty.
4-Castle: I like the design and looks of this.
5-1: Indeed, it does look like the difficulty is starting to ramp up. I worry about that many Hammer Bros. in one level (reminds me unpleasantly of 8-3 in SMB1), but I'd have to try the level myself to say for sure.
5-2: I think I already told you what I thought of this one on Skype.
Blue Switch Palace: Uh...it's a switch palace and it's blue?
5-3: Seems fine, but the music you used sounds way too "happy" for the setting (given it's a nighttime level, or at least twilight).
5-4: Nice music choice. I think the foreground aesthetics are a bit dull for the theme aside from the crystal decorations, but the level's not bad.
5-Ghost House: You know, there are still more things you could turn upside-down, such as the question-mark blocks (ExAnimate them). I do like the gimmick, though. Pity there's no easy way to make an entire level using Mode 7, no?
5-5: Neat idea using that auto-scroll sprite that way, though I would suggest giving the player more to do during the slower parts of the level (for instance, around 1:45 in the video).
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I'm working on a hack! Check it out
here. Progress: 64/95 levels.