Boost Mode (ブースト,Būsuto?, lit. "Boost") is a reoccurring technique that appears in the Sonic the Hedgehog series. When performing it, the users enter hyper-speed mode that surpasses their regular running speed.
When entering Boost Mode, the users becomes able to run at extremely fast speeds, usually leaving afterimages in their wake.
In gameplay, there are two ways to enter Boost Mode: the first one is by running at full speed for a while, and the other is by utilizing Dash Panels or horizontal Springs. However, Boost Mode is somewhat risky to use since the high speed makes the playable characters difficult to control. If the playable character comes to a rapid halt or slows down, the Boost Mode will be deactivated.
Sonic Advance 2
In Sonic Advance 2, the character is simply able to run significantly faster with increased acceleration while Boost Mode is in effect. The more Rings the player has obtained, the faster the character can enter the mode. Sonic can also engage this manually if he performs a failed Homing Attack and hits the ground running. For the entire duration of the move, the character can perform a Boost Attack which varies depending on the character.
Sonic Advance 3
In Sonic Advance 3, Boost Mode is basically the same as in Sonic Advance 2, but without the Boost Attacks. However, only speed-based teams are able to use it. If Sonic is the character's partner, he/she can manually engage it via Tag Action. However, if the character is partnered with Cream (except for Amy) and performs a failed Homing Attack and hits the ground running, then he will automatically enter Boost Mode.
Sonic Rush series
In Sonic Rush and Sonic Rush Adventure, both Sonic and Blaze can enter the Boost Mode. In these games, it is possible to enter Boost Mode by activating and then disengaging the Super Boost/Fire Boost while moving; when the Super Boost/Fire Boost ends, the player will be left in Boost Mode should he/she continue to move forward.
Sonic Colors (DS)
Boost Mode reappears in the Nintendo DS version of Sonic Colors. In this game, its mechanics are the same as the ones in the Sonic Rush series. When entering Boost Mode, Sonic briefly gives a rainbow-colored aura in front of him. However, when he is boosting over water, it becomes a blue aura.