In order to post scores on the leaderboard the player must be logged into either GameCenter or Facebook
The leaderboard displays the players personal best score from any one mission. Only active players scores will be displayed on the leaderboard, temporarily removing inactive scores from user who have not played a mission over a period of 72 hours. Players scores are not erased if they become inactive, playing another mission will reinstate the players best score and position them accordingly on the leaderboard.
Note: Only the players BEST score will be displayed, playing subsequent missions does not guarantee the player will achieve a better score.