Fun, addictive little game.
I quite enjoyed that :-) nice little game, but in the next version, maybe add some powerups or something, and maybe make the tubes actually do something (Possibly have a liquid of some sort rushing through the tubes, and you have to make the link it to a stopper or something so as not to spill any of it).
Very promising though, it was fun to play about with. The simple sound effects were good. Get some decent tube graphics, though, and you're all set ^^