Sonic Dash 2: Sonic Boom (known in Japan as Sonic Dash 2: Sonic Toon) is a free-to-play behind-the-back endless runner developed by Hardlight and released by Sega for Android devices on July 1, 2015 and for iOS devices on October 9, 2015.
It features character designs, locales, and enemies based on the Sonic Boom series, along with some new features (such as a multi-character team-based mode, special unlockable abilities, and magical helpers called "Sprites"). The iOS version was also launched with a companion Apple Watch smartwatch app that allows players to earn in-game rewards by taking real-world steps.
Only Sonic is available from the start. Each other character can be unlocked either through the game's premium currency or through limited-time events.