I like the ideas you got about features to add to such a classic game.
I have a few comments and suggestions:
- You could increase the levels faster, so the players would have more chance to see more of the new stuff. I played for a few minutes and was still stuck in level 1. Or maybe an option to start at a higher level would be nice.
- I think you need a repeat on the 'down' control so you can move the pieces down faster without having to tap your keyboard multiple times :)
- Extra sound effects would be a plus to the experience!