An Apocalyptic LitRPG It's been over a year since the System came to Earth, bringing blood and monsters in equal measure. Having left Whitehorse, John and his team travel down to British Columbia, running into new dangers from aliens and humans alike. Faced with new challenges and new enemies, John steps up once more to set things right and teach a few aliens why you never put humanity in chains. Cities in Chains is Book 4 of the System Apocalypse, a LitRPG novel set in a post-apocalyptic Earth that combines modern day life, science fiction and fantasy elements along with game mechanics.