Achievements-Complete Events
Once Upon A Time is an achievement that players can unlock after completing 5 events(*) (winning these events are not required). Players that have completed this achievement will be rewarded with 1 Icon Gold. Once Upon A Time is succeeded by the There Was A Racer achievement.

(*) To clarify, in game it's called events, actually the player has to complete races, as shown on page two of the players profile, races can be run more than once, the reward is given on completing the required quantity of races.