The sequel to the record-shattering Sonic the Hedgehog and Mega Man crossover is here! You saw what happened when Worlds Collide! Now brace yourself for when WORLDS UNITE! Sigma--the brilliant villain from the future--has fused the worlds of Sonic the Hedgehog and Mega Man together! Now he feeds on the super-planet's energy to become unstoppable! It's up to Sonic and Mega Man to raise an army to fight the time-hopping villain. Joining them are the Freedom Fighters, the Robot Masters, X and his Maverick Hunters, Sticks and her friends, and--Dr. Eggman and Dr. Wily?! But it won't be easy, as Sigma uses his powers to reach across space and time to recruit an army of his own! It's a battle of epic proportions to save the Unified World! Featuring the introduction of the STREET FIGHTER cast, including Ryu, Chun-Li, Guile and Ken! This volume collects WORLDS UNITE parts 5-8, including SONIC UNIVERSE #77, SONIC BOOM #9, SONIC THE HEDGEHOG #274, MEGA MAN #51 and selections from the MEGA MAN: WORLDS UNITE BATTLES and SONIC THE HEDGEHOG: WORLDS UNITE BATTLES one-shots and includes bonus materials such as creator spotlights, production art, and 16 pages of cover images.