The game begins immediately after its in-game comic strip prequel, where Amy is in the middle of a fight with Lyric the Last Ancient who wants the info she has on finding the Lost Crystal of Power. After dealing a blow that stuns him for a bit, Amy contacts Sonic to tell him of her findings, only to be knocked off guard by Lyric, (getting disarmed in the process). Despite her protests, Lyric manages to plant a device on Amy's head, knocking her unconscious as he introduces himself to an outraged Sonic. After destroying Amy's communication device with his tail, Lyric makes his getaway.
After completing Seaside Beach, Sonic meets up with Sally, Tails and Cream explaining the situation and asking for his help in tracking down Amy. Tails eagerly agrees and reveals his newly-developed form of technology that can allow the viewing of destroyed files. Sonic is glad at this fact, but then wonders how Sticks will react when she learns of Amy's capture. After finding their new friend Sticks the Badger, the duo tell her their current predicament, with Sticks nonchalantly running off to find Amy as they give chase. After a race, Sonic urges Sticks to join the team as teamwork is the only way they can win. Meanwhile, Sally, Tails and Cream manages to decipher some of Amy's research logs, which prompts them to head for the Scrapyard, where Knuckles last was. The group finds Knuckles without much trouble and the echidna is eager to help, claiming that they should get a move on. With the full team assembled, the group heads for Shadow Canyons, where they notice Shadow the Hedgehog standing off in the distance, only to run off. Wondering what he is up to, the group follows him, and after a race, he comes back to his senses and everyone realizes that he's been possessed by Lyric this entire time via a mind control device similar to the one used on Amy. After being taunted by a hologram of Lyric that comes from the broken device, Shadow skates off in hot rage, with the others agreeing to follow him into the Ancient Ruins.
After completing Ancient City, the group discovers that a large robot facility is hidden beneath the ruins, and is responsible for all of Lyric's robots. They decide to shut it down, and are ambushed by Metal Sonic while down there. Sonic races him, but loses and Sally, Tails and Cream shortly manages to track his movements and find that he is headed for the Volcanic Crater. Once there, the team finds themselves lost, but decides not to give up. After deciphering another of Amy's logs, they discover that a hangar of ancient planes is hidden in the volcano and decide to search for it. After finding it, the group heads off, and manages to escape the volcano, though Tails has some trouble steering the plane and ends up crash-landing on the Cloud Sanctuary, (much to an airsick Knuckles' relief). Meanwhile, it is revealed that Amy has regained consciousness and is adamantly refusing to translate the ancient language for him despite his orders, all the while claiming that Sonic and co. will come for her.
After Sonic, Sally, Tails, Cream, Knuckles, Sticks, and the freed Amy finally arrive on Lyric's airship, they being to flaunt the power of teamwork in front of the dastardly snake, only for Lyric to get an idea and trap everyone but Sonic in the same glass ball that Amy had been imprisoned in previously. Sonic gives chase, and after fighting Lyric, he frees everyone. Their rejoicing is cut short however, as Lyric regains consciousness and prepares a giant robot to finish the group off. Shortly later, Shadow intervenes and dismantles the mech, rendering it useless and kicking Lyric out the bomb-doors of his own ship (which Sonic had opened just as this happened). The team rejoices again, as Sticks gives a slightly incorrect speech about teamwork. The adventure over, Shadow walks off, claiming to be a loner and superior to Sonic. Sonic is dismayed over the fact that Shadow does not want to join them, as he thinks that he would make great addition to "Team Sonic". Sonic and Knuckles then get into a brief argument over what the team's name should be as the group begins the long journey back home.
Sonic Boom: Shattered Crystal is a 2D side-scrolling adventure platformer. Unlike its Wii U counterpart, which is more focused on 3D platforming and beat-em-up, Shattered Crystal places a bigger emphasis on platforming and puzzles, while each character has their own unique abilities to get them through the levels.
There are three different types of stages in Sonic Boom: Shattered Crystal. The adventure levels take up the bulk of the game and include the normal gameplay sections. They are large, mostly non-linear 2.5D stages where the player controls all four characters. The adventure levels are as well divided into two parts (the foreground and background) that run parallel to each other, which can be traveled between with the Slingshot. The Rivals Race are levels which are also played from a 2.5D perspective. Here, the player races another character down a linear course. Finally, there are the Worm Tunnels, where the player runs down an obstacle course at full speed. In the latter two level-types, only Sonic is playable.
The bottom screen of the 3DS has three uses: A character-select screen allows the player to tap on the portraits of the playable characters to switch to them (they can also be switched by pressing their corresponding direction on the D-pad). There is also a map screen that shows the levels in a Metroidvania-esque map format that highlights things like collectibles, checkpoints, slingshots, and the level's exit, as well as showing the percentage of the map that has been explored. Finally, there is a Level Stats screen that shows the obtained collectibles and the time and ring records of previous playthroughs of the level in question.
The game contains a variety of collectibles, some of which unlock special content for Sonic Boom: Rise of Lyric via connectivity between the two games. Game progression revolves around moving along the world maps, as well as the collection of Sonic Badges to access new levels. In addition, the player can earn Tokens which can be exchanged for collectible toys at Q-N-C's Toy Shops. Each adventure level awards three Sonic Badges and two Tokens, while the other levels only award one Sonic Badge and two Tokens. These objects can be earned in the following ways:
- Clear the level: Clearing a level awards one Sonic Badge.
- Collect all the Crystal Shards: Collecting all five Crystal Shards that are found in each adventure level awards one Sonic Badge. These shards can be brought to Sticks' Burrow to repair the Lost Crystal. The player's progress with the Lost Crystal is displayed on the level loading screen. Collecting all shards gives a special Token which can be exchanged for an unique toy.
- Collect all the blueprints: Collecting all six Blueprints that are found in each adventure level awards one Sonic Badge. These prints can be brought to Tails' Workshop where a set of six Blueprint pieces can be put together to unlock upgrades for the playable characters.
- Clear a level in a certain time: Clearing a level within a certain time awards one Token. The time requirement often varies.
- Clear a level with a certain amount of rings: Clearing a level with a certain amount of Rings awards one Token.
Both Sonic Badges and Tokens cannot be earned more than once per level. Other ways to get Tokens include connecting with other players via StreetPass, and playing a daily minigame in Knuckles' Hangout.
Sonic Boom: Shattered Crystal is divided into six island areas with eight adventure levels, six Worm Tunnels and three Rival Races divided between them. Each area has a World Map where the player can access said areas' levels and houses with special features. Travel between them is done through the Slingshot on each World Map. The areas levels include:
- Seaside Coast
- Shadow Canyons
- Ancient Ruins
- Volcanic Crater
- Cloud Sanctuary
- Sonic's Shack
- Tails' Workshop
- Amy's House
- Knuckles' Hangout
- Sticks' Burrow
- Q-N-C's Toy Shop
Rival Races Edit
Located through out the game are four Rival Races that the are the equivalent off boss battles. Like the Worm Tunnels only Sonic is playable.
- Seaside Race
- Shadow Canyons Race
- Facility Race
- Lyric's Airship
- Sonic the Hedgehog
- Miles "Tails" Prower
- Knuckles the Echidna
- Sticks the Badger
- Amy Rose
- Shadow the Hedgehog
- Metal Sonic
- Lyric the Last Ancient