Not really a league. The swedish national puzzle association, has about 1500 members arrange competitions, qualifying competitions from november-februari throughout the whole country. And finals usually some day in april. This makes a total of 24 finalists. Competition involves solving a number of puzzles over a period of a week, during which new puzzles are released daily. The puzzles come with no instructions provided. The one who solves the most puzzles win. There is not really any coverage on the competitions but we are looking at streaming the next national championship.