This story is a sequel to Singularity

A new tri-colored virus has spread throughout New Donk City, infecting many citizens and forcing the rapid development of a cure: Megavitamins. But not all is as it seems, as the viruses prove to be more intelligent than assumed at first glance. By a stroke of chance, a gateway leading to other worlds now exists in Dr. Mario's workspace, allowing the viruses to escape to Equestria. Now it's up to Dr. Mario to aid Princesses Celestia and Luna to rid their world of this microscopic alien threat before all of Equestria succumbs to their sickly influence.

A Singularverse story

Cover art by Mach-7 on DeviantArt.