This is a tree of Quoridor opening theory. Start from the first move and
follow a branch: each move on the list leads to the next position. You
can also play any legal move on the board yourself, and the tree follows
you off the book's lines too.
Every move shows how many games reached it and how often White won from
there. Switch the list to Best for White or Best for Blue to see what
actually scored, not just what gets played most. A move that's only shown
up a few times won't jump to the top because it got lucky once.
The opening is simpler than it looks. Both pawns start eight steps from the
far side, and if nobody ever placed a wall, Blue would win. The pawns meet
in the middle and White, being a move ahead, is the one who has to step up
and get jumped. That's why the first walls tend to go down right where the
pawns are about to meet. The good ones cost your opponent a step and cost
you nothing. For more, read Quoridor
strategy and the rules, or try the
ideas out on the puzzles.