NationStates is a multiplayer government simulation browser game created and developed by Max Barry. Based loosely on Barry's novel Jennifer Government, the game launched on 13 November 2002 with the site originally founded to publicize and promote the novel one week before its release. NationStates continues to promote books written by Barry, but has developed to be a sizable online community, with an accompanying forum board. As of 10 February 2024, over 8.96 million user-created nations have been created, with 289,625 being active.

A government simulation or political simulation is a game that attempts to simulate the government and politics of all or part of a nation. These games may include geopolitical situations, the creation of domestic political policies, or the simulation of political campaigns. They differ from the genre of classical wargames due to their discouragement or abstraction of military or action elements.