Oh wow, that's so neat... it reminds me a little bit of falling sand games, actually! No imposed goal, just a Puyo Puyo power fantasy where you get to build gigantic towers just to see them fall apart. It's interesting that this could never work with Tetris mechanics, or at least not at this same "infinite" scale - it's just a great big ridiculous testament to Puyo's unique flavour of falling blocks. 

interesting concept