Lockwater: Canal Puzzle

Lockwater is a canal puzzle made of soft clay: a row of stone chambers, a few wooden gates, and boats that must reach the flag of their color.

Tap a gate and the water on both sides flows until it settles at one level. Tap a boat and it sails through the open gates toward its flag. The catch: water never comes back. Every opening evens the levels for good, so the order you open the gates in is the whole puzzle.

• 100 levels in 10 chapters, each in its own light, from a warm morning to a starlit night
• A solver checks that every level can be won in the number of moves shown; match it for three stars
• Boats run aground in shallow water, and tall masts will not fit under low bridges
• Valve wheels that fill and empty side basins, a deep-hulled barge, and up to three boats sharing one canal
• The first levels each teach one idea with a wordless pointing hand
• When a canal can no longer be won, the level ends at once, so you never play on in a dead end
• Hints show the next move. You start with 3, get one back every 5 minutes up to 10, and can watch an optional video for 6 more
• Retries come back the same way, one every 5 minutes up to 10
• 25 achievements, also on Game Center
• Plays in landscape on iPhone and iPad, and on iPhone Duo folded or unfolded

Lockwater is free. A banner and an occasional ad between levels keep it that way; a one-time purchase removes them. Hint packs are also available.