The game follows the events of the second Robot City novel: Suspicion. The main character, an amnesiac who has taken the name of Derec, must search the city for clues to the identity of a murderer while also discovering the nature of the robot city itself. Eventually their path will lead them to one of several endings that determine the fate of the murderer and the city.
Most of Robot City is spent talking to robots in the city and reading archives. Game screens are static and viewed in first person. Piecing together clues will allow Derec to discover new locations, including some that the robots do not allow him to visit. To get to these Derec will have to walk the city's streets, a frustrating affair because streets are shut up and rebuilt seemingly at random by the nanobots that endlessly recreate the city.