Change Tetrads (Puzzle Pieces)
To change the tetrads from T and L shaped pieces to triangles, short bars and large squares, first complete all practice rounds. You will then have a red background.
Then get an "OK" rating in all modes except practice and multiplay. (When you get an "OK" rating, game options will flash green.
Once you have achieved an "OK" rating in all required sections, your background color will change to green. Then in all modes of play except practice, you'll see a little blue guy. He represents the default pieces. Click on him and you'll see a duck. This represents the new set. Pick one and get wet baby!
Floor Select and Background Color Change
First, complete all 16 practice rounds (8 1UP/CPU and 8 1UP.) Now go to the options screen and you'll see a new option called floor. This will let you chose from many different floor sets such as the Mona Lisa and the American Flag.
It also seems to change the background color of the title and options screens as well.