From Sonic Retro
The Boost (ブースト), also known as the Sonic Boost (ソニックブースト) or the Super Boost (スーパーブースト), is a move utilized by Sonic the Hedgehog in newer Sonic titles starting with Sonic Rush. It is a rapid-acceleration move which allows Sonic to travel at vastly increased speed, activated by the press of a dedicated button.
Boosting has several major effects, the most obvious being that Sonic goes much, much faster; while Boosting, the edges of the screen even blur in order to accentuate the effect. Sonic also becomes surrounded by a blue-white shock front, capable of smashing enemies or small obstacles out of the way and send them flying. Thirdly, Sonic's wake pulls in Rings behind him, an effect much like the Lightning Shield from earlier games. Using the Boost consumes energy, and the boost can be used for as long as there is at least some energy left, which is replenished by different means depending on the game. Finally, the Boost enables Sonic to hydroplane over the surface of any body of water; important for levels where there is a lot of water to traverse.
While using the Boost can make the player invulnerable to most enemies and obstacles, they are not completely invincible, as indestructible hazards such as spikes and fire can still cause damage, and crush hazards can still kill them. Boosting into unbreakable obstacles (such as walls) can also stop the Boost, and in some games will make Sonic fall over, taking several seconds to get back up.
Sonic Rush series
The first game to feature the move, Sonic Rush, refers to the move as the Super Boost (スーパーブースト) and is used by Sonic. Blaze the Cat can also perform the move, and her version is referred to as the Fire Boost (ファイアーブースト). The technique is performed by pressing or while on the ground, rushing forward and plowing through enemies as long as there is energy in the Tension Gauge. When the Tension Gauge is maxed out, the player can Boost infinitely for a short amount of time.
In both Sonic Rush and Sonic Rush Adventure, the player can crouch and roll during the Super/Fire Boost. This is useful when going downhill, as it allows for even greater speeds. The super-high-speeds of the Super/Fire Boost are necessary to avoid death in several places during the Rush games, like when pursued by giant boulders.
In Sonic Rush Adventure's Sea Stages, the Wave Cyclone is also capable of Boosting, which can be done by either tapping the Touch Screen twice or by pressing or as long as there is energy. Holding the stylus/button down will maintain the boost.
Sonic Unleashed marks the move's first appearance in a 3D Sonic platformer, where it is referred to as the Sonic Boost (ソニックブースト). In the daytime stages, Sonic can perform the move with the button on the Xbox 360 version, the button on the PlayStation 3 and PlayStation 2 versions, and by swinging the Wii Remote on the Wii version.
In the 360 and PS3 versions, the Sonic Boost is powered by Ring Energy, which makes the move's ability to draw in Rings doubly useful, and can be activated at any time. In the Wii and PS2 versions, the Boost Gauge is split into multiple chunks, and can only be used when the player has a full unit on the gauge; using the Boost costs one unit, runs automatically for a set amount of time, and the player will not be able to use another Boost until the first one runs out. Creative use of the Boost and jump platforms can enable Sonic to travel immense distances in midair; a fact extensively exploited by Sonic Unleashed speedrunners.
In Sonic Colours, the move returns once again, this time the move is referred to as simply the Boost. Instead of being fueled by Rings, it is tied to the White Wisps found in capsules, making it more of a power-up than a move. This forces the user to be more cautious on when and how to use the Boost, and allows the levels to be designed around more platforming than pure speed.
In the Nintendo DS version, the Boost is functionally identical to the Sonic Rush series. Collecting all of the Special Rings in this version of the game will unlock "Infinite Boost", which will allow Sonic to Boost as much as he likes, even if he runs out of boost energy.
The Boost returned again in Sonic Generations as a move performed by Modern Sonic, and the Boost Gauge is now refilled by collecting Rings, defeating enemies and performing Trick Actions. Recharging energy by performing Trick Actions will also refill the Boost Gauge past the maxiumum. Certain Skills can affect the Boost Gauge, such as doubling its capacity or enabling Sonic to boost infinitely at the cost of not being able to pick up Rings. The Boost can be used indefinitely while in White Space.
Compared to Sonic Unleashed, the Boost's radius for pulling in Rings is smaller, and boosting over water consumes a lot more energy than normal. When Modern Sonic transforms into Super Sonic, performing the Boost will allow him to fly, but doing so will drain his Rings a lot faster. In the rival battle with Shadow, Sonic can Boost into meteorites to shatter them and slow Shadow down when powered up.
In the Nintendo 3DS version, Boosting is similar in function to the Sonic Rush series in that filling the Boost Gauge to its maximum capacity will enable Modern Sonic to Boost infinitely for a short amount of time.
After its absence from Sonic Lost World, Boosting returns in Sonic Forces, though its fuel has reverted back to Wisps. In Tag Team stages, Sonic and the Avatar are capable of performing a special technique, known as the Double Boost, where the two characters boost together to clear through obstacles or to escape. Shadow the Hedgehog is also capable of using the Boost when being played as via the Episode Shadow DLC.