The backstory of Exodus encompass an alternative history of 20th century from 1939 to 2012, which is the year of nuclear war's outbreak.

In December 2012, on the winter solstice, a date prophesied by the Maya as the end of evolution, a date prophesied by Nostradamus as World's End, man chose to evolve by the process of natural selection through self extermination from nuclear fallout.

[3] The decade long War on Terror escalated to a series of short events between many warring nations that ravaged the known world on all sides, forcing humanity into an "exodus" that would last 20 years before survivors could return from fallout shelters to the ruins of civilization and start a new era of human civilization.

[2] Writing for Flamesrising.com, Megan Robertson gave a positive review for Exodus, praising its post-apocalyptic Southwest United States setting, Mayan-inspired backstory, sound role-playing game mechanics, and adequate product support.

[3] Jim Moreno from Geek and Sundry included it in his list of Fallout-inspired tabletop RPGs to try.