Endless Boost is the fourth Challenge Act of Rooftop Run Act 2 in the console/PC version of Sonic Generations. It is unlocked after clearing every Stage in the modern era and is playable only as Modern Sonic.
In this Challenge Act, the player has only 120 seconds to reach the Goal and the special feature is that Sonic can Boost for an unlimited duration. As a drawback however, Sonic cannot increase his Ring count above zero, meaning that getting once from an obstacle will kill him causing the player to fail the Challenge Act. The player must simply memorize the Act's layout of obstacles (which include Spiked balls, swinging blades, bombs, Spike Traps and Electric Generators) and avoid them accordingly. Upon completing this Challenge Act, the Endless Boost The time needed for a S rank is 00:50.