Such a neat concept! I greatly enjoyed playing this! It's got some nice tetris-like ideas but takes them to a whole new level! Also like others have said, the idea that the enemies can help and hurt, as can the blocks, is a really clever idea.
Just a little suggestions:
With shapes that are more than 3 blocks long-wide, it might be nice to have the hole be subdivided so the player knows exactly how many squares to collect. That way they don't have to go back and forth between the hole each time to check!
With difficulty curve, the 4th level introduced, (3-1 I believe it was? the one with the moving T shape) is quite a bit of a leap compared to the previous levels. It's an AWESOME level, but it might be better to have a level or two in between that introduce the multi-layered enemies and the moving shape as separate elements
And also, I think others have mentioned this, but a snap mechanic would be nice with aligning the correctly assembled shape with the hole.
But those are all really tiny things, compared to how unique and well made this game is! Really awesome job with this game! Keep up the good work!
-Sasha