Roleplaying Genocide

A month ago, a rift appeared above the skies of Asia and Eastern parts of Europe. Within a week, major cities and surrounding countrysides has become a war-torn field, 90% of the world has turned into any of an assortment of mythical creatures, some losing their memories and self-identity while others . Cities started to fill with skeleton, knolls, goblins and zombies. Then it spread to America, one of the biggest rifts opened directly above my house, my brother and I are the only ones that survived. Also, did I mention the new world has a new "system" that's the same as one of an MMORPG.