Unlike its Wii U counterpart, Sonic Boom: Shattered Crystal on 3DS is an experience that is much more reminiscent of a traditional Sonic game. It takes place with a 2D perspective and your goal is to get to the finish in typical Sonic style — unlike traditional Sonic games however, it's not quite as simple as that.
Sonic Boom: Shattered Crystal is separated into three different level types. The bulk of the levels are exploratory in nature and require you to scour the world as Sonic, Tails, Knuckles, and newcomer Sticks in search of Crystal Shards, Blueprints, and ultimately the goal. You'll have to switch between different sections using an Enerbeam Slingshot, most of which act as a checkpoint, and all of these sections take on a Metroidvania-style layout with patented Sonic speed added into the mix. Don't worry, though, this speed is much more regulated than more recent 2D Sonic capers, and is closer to Sonic's original, fairer pacing. Considering the fact that the evident priority of these levels is to explore, this pacing is an absolute must; it's good to see that the developer has taken more consideration into the style of the level than to just tear around at blistering speeds and impede the gameplay.
Each character's unique moves allow them to enter areas inaccessible by others in the team; this is never an obstacle, either, as you can switch between characters on the fly. Each character also moves at the same speed, but their other movements remain true to their personalities. Sonic is the most agile, able to dash short distances in the air; Tails is able to use air vents to fly as well as descend much more slowly whenever he wishes; Knuckles has more attacks and power than his friends; Sticks can use her boomerang to attack enemies from afar. Combine these abilities with the focus on exploration, in particular, and it prompts you to keep your eye out for landmarks and opportunities to switch protagonist.
The other two level types are much closer to more modern 2D Sonic outings, with an increased focus on speed rather than exploration. One has you speeding through the levels against an opponent with the same desire to reach the goal as you; the stages are more suited to this, and reward smooth gameplay but allow you enough time to react before an obstacle slaps you in the face. The other places you on a tubular track with the camera behind Sonic, similar to Sonic the Hedgehog 2's bonus stages; you're stuck on rails and have to shift between available tracks avoiding hazards and collecting rings. It's simple in its premise and actually works really nicely.
This game is certainly more difficult than you might guess; finding all the secrets in the exploratory levels is no easy feat, as once you use an Enerbeam Slingshot to move to another section you're usually unable to return to that area without restarting the level entirely. These one-way systems force you to really look at every detail and crevice, and you won't usually find everything in a single run. You also won't start the game with all four of the characters, which are required to find everything in a level due to their unique abilities; a playthrough of each level that is orientated around speed is also required in order to acquire all of the unlockables.
The levels where you race against an opponent are probably the easiest of the three, but they're still a lot of fun; the tubular levels are simple to finish, but difficult to complete entirely. In order to complete these latter levels fully you'll have to collect every single ring and boost as much as you can, which really ramps up the difficulty.
This title isn't all sunshine and roses though, and suffers from a number of niggling issues. You'll have unlocked all the characters within about an hour and a half of gameplay, meaning replaying previous levels to find all the secrets happens too quickly for the experience to be particularly engaging, and would perhaps have been better if you unlocked them in more of a staggered manner. Even so, that still wouldn't take too long, as the main game is decidedly short. If you decide to unlock all of the secrets you'll get a few more hours out of it, but it feels rather like artificial padding, and it's required if you want to unlock the final stage — not a great idea for any younger gamers that would find this frustrating.
The visuals are also nothing to write home about. The characters look reasonable and the environments are pretty enough, but we feel that we and the gaming public have been spoilt by Super Smash Bros. for Nintendo 3DS, and the graphics aren't offensive enough to detract from the enjoyment of the game. You'll also not be troubled by the irritating voices from the Wii U version; instead grunts and whoops are the order of the day, which don't grate at all, especially compared to the 'quips' in Rise of Lyric.
There's plenty to enjoy in Sonic Boom: Shattered Crystal, but it's nothing revolutionary. It's one of the better Sonic outings of recent times, but unfortunately that's not saying an awful lot. If you're a Sonic fan or you enjoy platformers, you can do an awful lot worse, and this may be one to grab should the opportunity or a bargain price arise.