Equestria is at risk, Discord has teamed together with all of the rogues and villains of Equestria. He demands to take over Equestria in the most awesome way possible, a series of races around Equestria. Why? Because it's just awesome. Celestia calls her greatest heroes, the Elements of Harmony to challenge Discord at his own game.

Think Mario Kart meets humanized ponies.

(Credit to Superpinkbrony12 for the title)