One of my blocks fell through the floor, and a new block never came. I think it was because I tried to move downwards as I was arriving at the bottom row.
I have not written much python in my life, but this looks like a pretty compact implementation of Columns II. It's impressive that this whole thing is less than 200 lines of code.
What made you decide to create this particular game based on the theme "Pocket"? Is there a way to "pocket" falling blocks to save them for later, like in Tetris?