Sonic the Hedgehog is the fastest thing alive. Mega Man is a super-fighting robot. Together they are the coolest, bluest heroes ever! Blue Blur and Blue Bomber meet for the first time in the crossover event When Worlds Collide! Dr. Eggman and Dr. Wily have crafted a twisted pocket dimension--the Skull Egg Zone! Sonic, Mega Man, Tails, Proto Man and Rush have found their way into the zone, but how will they find the Doctors in this nightmare world? To make matters worse, Sonic's friends have been turned into the eight menacing Roboticized Masters! Can Sonic and Mega Man overcome these fearsome robot warriors? Can Sonic's friends be saved? And what new weapons can Mega Man gain from this fusion of Eggman and Wily technology?