The Master NXT is a being that has been corrupted by the Maelstrom. After he was corrupted, the Master NXT took advantage of the fact that Robot City had no proper firewall and began to spread the Maelstrom infection in a way that only non-organic beings, such as the robot citizens of the city, are susceptible to its corruption. Once he corrupted some robot citizens into Infected Citizens, the Master NXT built the stronger, faster, and unstoppable Separator robot to do his bidding and disassemble law-abiding citizens. Although robot citizens such as Unit 16 and Unit 64 receive help from players in smashing his Infected Citizens and Separators, they know that their victory is only temporary and that they must stop Master NXT himself before he takes over all of Robot City.