With some fine tuning, Sonic Heroes' team-based mechanic can be an excellent step forward for the series.
You take control of one of four teams of three and go through 14 different stages at great speeds. To sum up each team's stories: Team Sonic (Sonic, Tails, and Knuckles) are off to stop Robotnik in three days. Team Dark (Shadow, Rouge, and Omega) are off to get revenge on Robotnik. Team Rose (Amy, Cream, and Big the Cat) go out in search for their friends. Team Chaotix (Espio, Charmy, and Vector) is doing various tasks for a client. With the exception of Team Chaotix, all you have to do for each team is get to the goal ring as fast as you can, like you do in past Sonic games. With Team Chaotix you have to do specific missions. There are a total of 14 stages to go through in the game. Unlike the two Sonic Adventure games, the game ditches treasure hunting and mech-walkers in favor of a much faster paced experience and you no longer need to go through a hub world. Unfortunately, you'll be going through the exact same stages as all 4 teams, with only slight differences in their design and difficulty, which makes the game feel very repetitive.
Each of the four teams consist of three types of characters: Speed, Power, and Flight. Speed characters can perform homing attacks, create whirlwinds to send enemies in the air or launch themselves up poles, and most can wall jump and perform a light speed dash whenever they come close to a trail of rings. A Power character can break down certain destructible objects, launch their teammates as projectiles, glide down to safety or up to a higher point using a fan, and can easily clear out large crowds of enemies and large mini-bosses. Flight characters carry their teammates up to higher paths and take down out of reach enemies. The game also features a basic level-up system. By defeating enemies or destroying item boxes/balloons you can collect a red/blue/yellow orb. The color of the orb goes with the corresponding character (blue orbs are absorbed by Speed characters, etc.). Each character can have a max of three orbs per stage. Collecting orbs can increase the attack power of each character, which makes certain enemies a lot easier to deal with. The concept of this team mechanic is interesting to say the least, and the gameplay still manages to retain a hectic and fast pace that Sonic is known for.
Returning for the first time since Sonic 3D Blast come special stages. Found in each level is a key you can collect. Once you grab a key, you just need to reach the end of the level without taking any damage. The keys in Act 1 of each area take you to a special stage where all you have to do is collect multicolored orbs and boost your way to the end before time runs out. However, in Act 2 there is a key that takes you to a special stage where you race to catch a chaos emerald before it reaches the end. Collecting all seven emeralds, no matter which team you get them as, will unlock the last story.
Control is, sadly, not as satisfying or smooth as it was in the Adventure series. Turning tends to feel sluggish and often you'll end up accidentally falling off the edge of a cliff because the characters can go to max speeds in a matter of seconds. This is especially made true for the Special stages. Control feels stiff and trying to maneuver around bombs and collecting as many orbs as you can can be frustrating. Not only that, but you are constantly having to mash at the boost button, which can get very tiresome in the later special stages. The camera works as it should most of the time, but in the unlikely event you want to freely control the camera it tends to want to zoom in on the characters and can sometimes lead to accidentally switching to first person view.
The game also features a two player option, which only consists of two game modes: A battle mode where you try to beat up the other team and a race mode which is pretty self explanatory. Let's just say that you aren't missing anything. The 2-player option just feels rushed and it certainly won't appeal to anybody.
Graphically, the environments are what you would expect in a Sonic game: Bright, colorful and well-designed. Very rarely will you encounter slowdown. The game also features some beautifully rendered cutscenes every now and again. The character models look good (albeit rather shiny) and animate nicely. The music is one of the game's biggest highlights, featuring lots of catchy and upbeat soundtracks as well as some awesome Sonic Adventure-styled guitars. Unfortunately, the voice acting is mediocre at best and the dialogue is just painfully kiddy.
To sum things up:
PROS:
-Colorful graphics with smooth framerate
-Interesting team mechanic that fits with the fast-paced nature of the game
-Nicely designed stages
-Great music
-Strips away more annoying parts of the Adventure games
CONS:
-Mediocre voice acting and kiddy dialogue
-Control quirks ( a problem with special stages)
-All the teams have the exact same levels with only slight changes to suit each team.
-Poor 2-Player option
If anything, this game is only meant for Sonic fans looking for something new. The game's team mechanic shows plenty of promise; it simply needs fine tuning.