"Sonic Generations" is a platform video game developed by Sega that celebrates the 20th anniversary of the Sonic the Hedgehog franchise. Released in 2011, the game features both 2D and 3D gameplay, allowing players to control classic and modern versions of Sonic. In "Sonic Generations," players navigate through various levels called "Acts," which are inspired by previous games in the series. The storyline involves Sonic and his friend Tails traveling through time to defeat a mysterious enemy and restore the stolen memories of their past adventures.