Discovering an element known as Ragnium, Eggman starts harnessing for himself, using it to create robots that can allegedly outrun Sonic and his friends while also damaging the environment in the process. Meanwhile, D-Fekt, a rejected robot Eggman created to search for Ragnium, starts using his magnetic powers to try and become more powerful. Naturally, it is up to Sonic and co. to stop Eggman and D-Fekt and restore balance to the environment.
See also: Gameplay of Sonic Boom: Shattered Crystal
Like the previous 3DS entry, Shattered Crystal, Sonic Boom: Fire & Ice is a side-scrolling platform game in which Sonic and his companions fight their way through various stages. In addition to Sonic, Tails, Knuckles, and Sticks, Amy has been added as a playable character. Like the previous game, players can switch between characters at will in order to use their unique abilities such as Tails' flight, Sticks' boomerang, and Amy's hammer. A unique gimmick in this game is the addition of fire and ice elements, which apply both to the level environments and character abilities. For example, Sonic can infuse himself with fire to break ice blocks or surround himself with ice in order to freeze water, alternating between the two at will. The game will also feature various special stages, bonus minigames, challenge rooms, and local two-player modes.
Sonic Boom: Fire & Ice was first announced on June 9, 2015. Sega producer Omar Woodley has stated both Sega and developer Sanzaru Games have been learning from their experience with Shattered Crystal, which received mostly negative reviews upon release. One of the problems they identified was how, even though the game was targeted towards children aged 7–11, fans of classic Sonic games picked up the game and had a harder time getting into Shattered Crystal's lengthy exploration-based levels. As such, levels have been made shorter and include paths to better suit gamers who prefer speeding through levels, in addition to explorational elements.
- Roger Craig Smith as Sonic the Hedgehog
- Colleen Villard as Miles "Tails" Prower
- Cindy Robinson as Amy Rose
- Travis Willingham as Knuckles the Echidna
- Nika Futterman as Sticks the Badger
- Kirk Thornton as Orbot
- Wally Wingert as Cubot
- Mike Pollock as Doctor Eggman