- You may be looking for a different Challenge Act, 300% Boost Gauge Challenge.
200% Boost Gauge Challenge is the second Challenge Act of Sky Sanctuary Act 2 in the console/PC version of Sonic Generations. It is unlocked after clearing every Stage in the classic era and is playable only as Modern Sonic.
The Act takes place in a heavily modified version of Sky Sanctuary Act 2. The stage's layout has been modified by barriers and additional platforms, and Propeller Springs make a comeback. The player is given a finite (though greatly increased) amount of Boost with which to complete the Act.
In this Challenge Act, Sonic must reach the Goal Ring as quickly as possible before time runs out. His Boost Gauge is doubled, so he can reach the goal slightly more quickly, although the Boost Gauge cannot be refilled by any means. However, if Sonic wants to reach the goal in one minute ten seconds for an S-rank, he will have to rely on the Boost to reach shortcuts that are otherwise inaccessible. The high number of Eggrobos that stand in his way often help Sonic rather than hinder him, for they can be attacked to help reach other shortcuts. But a Homing Attack can slow Sonic down, and only by using his boost with timing and precision will he achieve an S-rank.