The Shiller Opening is great because it is so easy to see what the opening does for you and it exemplifies some of the best advice in Quoridor. Let’s go over the opening and then talk about how great it is.
The Shiller Opening
After both pawns have marched to the center of the board place a vertical wall behind your pawn touching the back edge of the board.
This wall creates two paths for your opponent while maintaining one path for yourself.
The Shiller Opening is named after Larry Shiller, a math educator and Quoridor Champion. Shiller also has given some of the best Quoridor advice that I have come across. Shiller writes, “In Quoridor the winning mid-game strategy is to minimize your paths to the goal while maximizing your opponent’s paths to his or her goal.”
Let’s compare path counts for a player using the Shiller Opening and a player using the Standard Opening.
As you can see, having your rear wall touch the edge of the map significantly cuts down on the paths available for yourself. The second board is a bit messy, but you can see that because the only wall on the map is behind Blue, there are three possible ways Blue can travel around the wall and to his goal.
One strong response to the Shiller Opening is to place down your own Shiller.
You can also try and bock the Shiller Opening with a vertical wall leaving a gap the your opponent’s back court.
In this case the vertical e4v leaves a gap in Green’s back court. Of course Green can close this, but it will cost a few more walls.
Screenshots from Martijn’s Quoridor App