Not bad!
Unfortunately not particularly great either :S.
Lets see. Like Soilheart said, this game isn't particularly new. But we all know that ;).
It would have been nice to see a little more originality though.
I mean, you can see that you put work into this and that it wasn't easy to make. Making puzzles can be harder than actually solving them.
True it got my mind working. But after having beat a decent amount of levels and basically only finding buttons and nothing else, kind of dissapointed me.
People normally try to introduce some certain aspect that makes their game unique.
And yes, you added the Themes page. Changed sum graphics, that's cool don't get me wrong. But what such classic games like this really need is uniqueness in gameplay ;)
The graphics were good though. And the game worked smoothly. It surprised me though how in some levels you were supposed to "glitch" on purpose and kinda run through moving blocks.
As for the beginning of the game. I must agree that giving those instructions first thing before the menu isn't what's normally done. But once i'd read what it said, and seeing no "Continue" (or similar) button. First thing i thought of was hitting M. Don't think that's too hard a deduction to make really... But anyways.
As for the music. Well, it's OK really. The music's good. But after a while it gets pretty repetitive, as the music clips your looping aren't particularly long. And i ended up just muting it... :S. So see what you can do about that ;).
And one more thing. I think it would be a good idea to add a slightly more precise saving feature. Your theme system is ok. But if someone accidentally hits M, right before finishing a theme. Their pretty much doomed to beat the whole thing again. So a manual saving menu or automatic level by level save would be pretty nice :).
All in all, the games not bad. But not worth a great score either. You get a 6/10 and 3/5 from this critic.
Hope you find the review helpful. And keep it up. Some of your other games are quite good :)
Cheers! ^^