Board Game Arena

As of now the winner gets 1 points, the others get 0. So rating change is irrelevant to how close were the loser to their winning edge. Diversified scores would give some incentives to equalize the situation, making it less obvious who's gonna win. It could be just as simple as that: each player starts with 100 points (stars) and when the game ends the number of remaining squares to the winning edge of each player is substracted from their score (so the winner keeps their 100). This way rating changes can be made proportional to individual performance.

nb: penalty distance should be counted as real distance taking walls into account, not as Manhattan distance, obviously.

Does it really matter who gets 2nd place ?
4-player Quoridor is a fun quite random game, I don't think it calls for a more advanced ranking system.