I'm stuck on level 38 (Hard) - I've spent a total of about 3 hours shuffling the blue piece around without luck, so I'm getting a bit fed up of it. I've found a couple of arrangements which let me get all but 1 squares worth of snake out of the way, but sadly, that's not enough :-)
I've completed all the other levels - it's a very nice game overall!
Any hints, anyone?
The following victorious comment may contain spoilers :)
Wow, I didn't expect that to work. I was trying for a much more "packed together" layout all the time. Somehow it's pretty hard to see when a path is "snakeable" without gaps. The solution turned out to be simpler than I ever imagined.
To lexaloffle: It might be nice for future versions if you got some sort of a 'well done' screen when you cleared all the levels. Nothing fancy necessarily, just an acknowledgement that you've cleared all the levels in the game would be good, I think.
I think I had the same problem trying to solve it as Gray - I was up to hundreds of moves shuffling things around, attempting to pack everything together.
In the end, it only took me 11 moves:
I am crying "Uncle" on the following Rooms on the Hard Level:  32, 33, 38 & 40.  I copied a 29 moves solution to Room 40 from a post of Gray's. That was very helpful.   I tried copying the above solution for Room 38 from FredFish.  For some reason the above solution does not copy to my clipboard.  When I tried to "paste replay" in the Options menu of Room 38 I get a message saying there's nothing on the clipboard (altho my desktop shows the above text is in my clipboard).  Is the above text correct?
I have v 1.0 now so I'll be looking forward to the new version.  I truly enjoy the puzzles; eating chocolate squares is so challenging and yet so sweet!  No need for violent, "kill 'em all" graphics.  Thank you!
With the exception of 40, I was stuck on the same levels as you by the end, neraks1. I needed the hints here to get through 38, and it took me several more days to solve 32 and 33.
33 Hard has about a million different ways to get very close, but I've only found one spot to break through to the center dark chocolate and still finish the entire puzzle. 32 Hard takes a lot of patience, and a bit of skill at the start to earn enough room to maneuver.