Sonic 20th Anniversary

Sonic 20th Anniversary celebrates the anniversary of the release of Sonic the Hedgehog. Sega advertised it as a time-limited app created specifically to celebrate the anniversary year, and withdrew it from the App Store at the end of 2011.

The app's biggest attraction is the game Sonic the Sketchhog, whose international release was exclusive to this app. A simple infinite runner, it features a sketchy hand-drawn Sonic running through a cute rendition of Green Hill Zone set to a relaxing music box rendition of the first stage theme from Sonic the Hedgehog 4: Episode I. The player is scored based on the number of metres travelled, the number of rings collected, and the number of enemies defeated; an online high score list allowed players to compare their high scores with their friends.

The app's other primary gaming feature is a one-level time-limited demo of Sonic the Hedgehog 4: Episode I, which had been released the previous year. It also featured weekly free downloadable wallpapers and a news feed featuring news about Sonic's 20th anniversary.