I've finished the first 4 levels as well as the timed levels.
I think my main gripe with the game would be the butterflies. They're interesting for sure, but very difficult to predict and deal with. I forget which room it was, but it had moving boxes and occasional waves of six or so butterflies. I found it to be the most difficult room in the first four levels (in part to the lack of a checkpoint). I think I read elsewhere in this thread that the butterflies are getting an AI boost so they will fly away and return to the player when they come too close. I don't think that would be a good idea, as they are incredibly powerful creatures as it is. I think becoming useless when too close to the player is a very good weakness for them to have. Just imagine a player having to protect himself with a wall of once-hostile butterflies!
There were a couple of minor bugs I noticed. It's been a while since I played, so I don't have the room locations on hand. Sorry.
In one room where you meet a character, there are fires around. If you step on the fire and die, when you restart the room, the character disappears. Perhaps the fire shouldn't kill you, since you can always undo from it, and it just might prove to be an annoyance.
Also, there is a bit of a visual glitch whenever you try and move your character against a moving ball. For example, if you're on the left side of a left-moving ball and try to move right, you'll see what I mean. And if you keep trying to move to the right for several turns, the visual glitch just gets weirder. It's hard to explain it exactly, so you should just try it.
As was mentioned before, the timed levels are interesting in their own right (I found myself having to play in a way I'd never played before), but it seems like computer speed really makes a difference with these levels. Take that into account if you decide to make any more of them.
I also suggest you have someone help you out with the scripting. The story idea is interesting, but the execution seems a little unprofessional. A solid translation, proper punctuation, and perhaps finding a context for the jokes within would help a lot on that front.
Overall, I'm looking forward to more of this. This game is looking fabulous so far!
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