"Pump and dump". You buy as many tickets as you want to play games during the qualifying period. Your highest score on each game is ranked and you get points based on the ranking of your score on each game. At the end of the qualifying period, the top 12/16/whatever players move on to finals which typically work much like the PAPA finals (groups of 4, 3 games, 4/2/1/0 points for 1st/2nd/3rd/4th on each game). This format is used a lot for major events partially because it cranks the prize pool through the roof.