Pipe Flow

Pipe Flow puts a slab of riveted iron in front of you, studded with cast brass, copper and verdigris fittings: straights, elbows, tees, crosses and capped ends, each one a quarter turn away from where it needs to be. Tap a tile to turn it. Join the red valve wheel at the top to the brass tank at the bottom, and when every joint lines up, open the valve. The water runs through tile by tile, glowing and bubbling in the elbows, filling the sight glass on the tank. Get one joint wrong and it sprays through the gap with a hiss of steam, and the run is over.

One hundred and twenty boards are laid out across six workshops. The Basement starts at five by five and asks only that you read the pipe. The Boiler Room stretches the runs. The Pump House bolts some castings down in cold iron so they will never turn. The Clock Tower adds gear tiles that drag their neighbours round with them, so a single tap can fix three joints or ruin them. The Waterworks runs two colours of water at once, and they must never share a pipe. The Grand Engine is ten by ten with all of it at the same time. Every board stores the exact number of turns a perfect solve takes, and three stars go to anyone who does not waste one.

There is a Daily Pipe, an eight by eight board that is the same for everyone on the same day, a three-minute Rush of quick five by five boards, and Zen, which is endless and does not count your moves at all. Undo walks back a turn at a time, restart puts the slab back the way you found it, and a hint picks out one casting that is still facing the wrong way. It takes taps, clicks and the keyboard alike, it lays the board out down the screen on a phone and across it on a desktop, and your stars are kept in your browser so the workshop is where you left it.