For the series’ 20th anniversary, Sonic Team devised a time travel plot that sees the shorter, pudgier Sonic of 1991 meeting his modern counterpart and taking on stages from the history of the series. Classic Sonic’s stages are all 2D designs, while modern Sonic refines the Unleashed/Coloursplatforming template. Re-imagined versions of stages like Green Hill Zone and Chemical Plant Zone are thrilling to speed through as modern Sonic, and even the less fondly remembered games inspire good stages, such as Crisis City. The game is quite short and a couple of the boss battles are weak, but it’s a fitting celebration of the series and a rather good platform game overall.