Top 10% of minesweeper game participants make it to the next League every week.
Results are drawn each Sunday night (00:00 PDT). So, every week 10% of all minesweeper players will pass to the next League.
Those who made it to the next League can still play the minesweeper game at Home Station and the settlements of all the previous leagues, but they won’t be getting any horseshoes for doing so.
In order to play in a new League you need to become the best in the previous League and turn the land where your target League is held into a Settlement.
New Leagues will be appearing in Klondike every now and then. So far there are 5 Leagues available (at Home, in Ukhty, in Polar-Side, in Khanbulat, in Sunrise, and in Nord-Pas).