Originally released in 2011, Sonic Generations stood out for not only including both Modern and Classic Sonic but also for its fast-paced gameplay and passion-filled level design. Now, as the game is set to celebrate its 13th anniversary, Sonic X Shadow Generations brings it back and adds one more hedgehog to the mix. Shadow the Hedgehog is being made playable with a completely new solo campaign dubbed "Shadow Generations," which is effectively a game within the game.