The V.I.R.A.L. Series

Veracity

A world not too far removed from our own.  Veracity has cities with busy streets and cars carrying people from place to place.  Unlike our world the citizens don't fear one another and each and all respect the system.  The only threats come from unruly mutations of the files.  Viruses.  The viral threat is managed by huge corporations known as Antiviral (AV) companies.  Within the AV companies, there are detectives who track the viruses and try to stop them before they become too large, and there are 'response' teams who act to quell viruses who have already burst out into action.  There are specialists on all teams, including melee combatants, marksmen and World Weavers who manipulate the code itself.

Avalon

Unlike Veracity, Avalon is a world set in a medieval-fantasy scenario.  They face more viral threats than the other worlds and so their cities are built for siege and their orders of warriors are vast and well trained.  There are many races of files in Avalon, rather than the almost entirely human population of Veracity.  They are also far more in touch with the code of their world, and so magi from Avalon are known to be some of the best in all the system.  Viral creatures have been known to roam wild in Avalon, and there are even some viral societies, so war is not unheard of.

Retra

Dissimilar still to both the worlds before, Retra is a land where cities fly using great, glowing engines and the races have learned to move their consciousness into machines.  Retra's technology, in the sky-cities, is unrivalled.  In the surface cities, people dedicate themselves to the code, and so the magi of the Retran world are equal to those of Avalon.  They do not have so many strong warriors in Retra, but the sheer technological and magical force they wield means that there are few viral threats.