Needs to stand out
I like Tetris as much as the next guy but this doesn't meet my inner Tetris fan.
You need to include more in your Newground type theme. The background and graphics fit it, but it could include more backgrounds and some NG characters.
It misses some basic Tetris elements as well, such as the hard drop and the display for what will be your next piece.
There are a lot of Tetris clone games on the internet, and nice attempt at adding a NG theme to attract more people, but have more to it.