When joining a Ladder, a player is placed at the lowest rank.
Players can only challenge other players on the Ladder if their ranks are within either 1/10th or 40 of the total Ladder ranks.
Ladder challenges cannot be declined or canceled.
Ladder games are given 3 days per turn.
Only one active Ladder game is allowed between a pair of Ladder players (you cannot challenge any player with whom you have an active Ladder game).
There is a maximum number of Ladder games you can have active at a time. The default is 8 Ladder games.
At the end of each Ladder game, the players are assigned a new rank based on the ranks of the players and the outcome of the game.
If the winning player has a lower rank than the losing player, they are moved up half the distance between their rank and the losing player's rank. The losing player is moved one position down. (For example, if the winning player was 10th and the losing player was 4th on the Ladder, their new ranks will be 7th ((10+4)/2) and 5th (4+1) after the game).
If the winning player is directly below the losing player, their ranks are swapped. (i.e. the winning player is moved one position up, and the losing player one position down).
If the winning player has the higher rank, they are moved one position up and the losing player is moved one position down.
If one of the opponents is no longer participating in the Ladder at the time game ends, the other player is moved one position up in case of a win or one position down in case of a loss.
Players are automatically removed from the Ladder if they have 3 timeouts in a month (to avoid further losses since Ladder challenges cannot be declined).
Players can lose their rank (move down the Ladder) without finishing any games, due to other players moving up the ladder after winning their games.