Original idea! This game has the potential to make very cool puzzle levels. The issue is that there is not enough content in the game. right now there is solid blocks, transparent blocks and spike blocks., which makes the game very 1-dimensional. Meanwhile there is the potential to make 14 different combinations, so you could really get creative there!
I think there should be an apparent grid, because its hard to tell where the tiles are.
There were a lot of performance issues with your game, have you tried to optimize it? Whenever I would click a button it looked like the game crashed, and Chrome would slow down to a crawl. There were some issues with the music too, it sounded screechy and glitched at some point.
Anyway, congrats on submitting!