Celebrate 50 issues of Mega Man with the latest chapter in the globe-smashing Sonic/Mega Man crossover event! 'Worlds Unite,' Part Four: Act One comes to its mind-blowing conclusion! Sigma's plan reaches its first stage, and the worlds of Sonic and Mega Man have fused! It's definitely going to take more than one hero to stop the threat from the future - maybe even ten! Sonic, Mega Man, X, Sticks, the Freedom Fighters, Robot Masters, and Maverick Hunters - Unite! Plus, stick around for a special bonus anniversary story as Mega Man and X meet for the first time! Featuring a wrap-around cover from the legendary Patrick 'SPAZ' Spaziante, plus five variant covers from Edwin Huang, Irvin Rodriguez, Patrick Thomas Parnell, Roger and Idalia Robinson, and part 4 of the epic 12-part connecting variant cover series by artist Ben Bates!