City of Villains is a standalone expansion to the popular MMORPG genre, allowing players to immerse themselves in the role of a villain. Released as an 'expanshalone', it introduces five new character archetypes exclusive to Villain characters, expanding gameplay options significantly. Players can explore new maps and engage in player-versus-player (PvP) combat in newly established PvP Zones, enhancing the competitive aspect of the game.

The retail version of City of Villains included four CD-ROMs for installation, a limited edition HeroClix figure, a detailed poster of the Rogue Isles map, and a serial code for the game along with a complimentary month of gameplay. Since its acquisition by NCSoft in 2008, ownership of either City of Heroes or City of Villains has allowed players to access both titles without additional fees, providing a seamless experience for fans of the franchise.