An interesting idea that seems a little bit unfinished. I like the idea of a spider escaping a Tetris game, and you really nailed the movement and sound effects for the spider. Also, the red lines to show where blocks will fall is a nice touch.

It could be more clear if there were animation for the falling blocks, or maybe a sweep across the top of the screen so we get a feel for the timing of the blocks as they arrive.

Also, there are plenty of rampant bugs, and the easiest way to cheese the game is to just crawl up the sides. Not sure that should be allowed.

But the idea is cool. With a bit more work and polish, this could be quite interesting!