State of Origin is the best all-star game format

In Australia, Rugby League is the traditional game of the state of New South Wales. The state of Queensland became the next area of the country to fall in love with the game.

Each year, in the middle of the regular season, they play a three game all-star series called State of Origin. The best players from the 18 teams in the league are selected to play for either Queensland or New South Wales based on which state they were (a) born, (b) played school rugby or (c) received their first professional contract.

The games are intense, get double the attendance of regular season games, and I believe is the highest rated TV event with the lone exception of the Australian Rules Football grand final.