Pipes is a classic in the puzzle world.
Select one of the 6 difficulty levels (actually 12 as for each you can activate wrap mode, making it MUCH harder...) and try to light up all the flowers...
Turn the pipes by clicking on them, and try to bring water throughout the whole board in as little time as possible.
http://www.xflib.net/index.php?action=games&name=Pipes
