Blue
White
· you
Tap the wall again to confirm
Every puzzle is a position from a real game where the side to move has a forced win, and exactly one move keeps it. An exact endgame solver checks every legal move before a puzzle is published, so there is never a second answer it forgot about: any other move loses against perfect play.
The answer can be a pawn step or a wall. Sometimes it is the move that looks least like an idea: running for the goal when a wall seems the obvious play, because every wall in reach loses.
Sign in and your first try at each puzzle is rated, like a game against the puzzle: solve it and your puzzle rating goes up, miss it and it goes down. The best solvers are on the puzzle leaderboard, and the Daily Challenge is one puzzle a day, the same for everyone, changing at midnight UTC.
For the ideas behind the moves, read Quoridor strategy, or test them against the computer.