A Thirteen pool tracks the score results of MLB (Major League Baseball) teams. The maximum number of participants is the number of teams in the MLB – 30 (or a whole number fraction of 30 if players get more than one team).

On the day the pool begins, each participant is randomly assigned a team. Any games played on, or after, that day count towards the pool. Whenever a player’s team ends a game (win or lose) with a final score of 0 through 13 (inclusive), that player gets a check-mark for that number. The first player to get all 14 check-marks wins the pool.

Once teams are assigned, they will not be changed for the duration of the pool, regardless of injury, or any other event that may make the team unable to play.

A player must get all of the following numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and 13.
In 30 player pools, each player gets 1 team. In 15 player pools: 2 teams. 10 player pools: 3 teams. 6 player pools: 5 teams. 5 player pools: 6 teams.

In a pool with multiple teams, each team is separately competing in the race for 14 checks – the individual team results are not combined. The player only needs one of their teams to win, and they are the winner.

The pool stops the moment any player achieves all 14 numbers. Any game scores that finalize after that time are not considered, since the pool is already over.

Scores are finalized using a snapshot of the MLB scores taken approximately every 10 minutes. All final scores found in the same snapshot will be treated as if they occurred at the same time, even if one actually slightly preceded the other. In very rare cases this allows multiple players to tie if they each earned their final missing score during the same 10 minute window.

In the event that the pool runs to the end of the regular season and no players have collected all of the required numbers, the player(s) with the most numbers win.