2009-08-22 (updated 2012-04-03)
You spin the various pipe pieces to allow the "droplitz" to reach the U-pieces. When a path is formed, the pieces are locked in and the bonus droplitz passes through it, destroying the pieces and incrementing the level number. This is repeated until you either run out of droplitzes or the pieces generated to replace the ones destroyed do not allow any paths to be formed (a.k.a. bad luck).