Today's the 25th birthday of Tetris. I believe writing Tetris clone is one of the best ways to familiarize oneself to a new language or a platform. It's not completely trivial and it lends itself well to learning language specific constructs like iterators and closures.

I've been hearing about Scala, and finally decided to read some docs and write a Tetris clone. So, this is my first Scala code. I did try to use functional constructs, but am sure there are lots of things I can improve to do it more Scala way. Please give me suggestions using comment. Also other submissions of Tetris clone in Scala are welcome too.

I'm aware that the actual question itself is somewhat subjective, but I think this is of some value since others can use this as example (or anti-example) code.

Edit: Let me rephrase the question. What can I do to make the code more Scala-ish?