They can be single-player or multiplayer.
They also usually take place in unique locations. They can include new items, weapons, characters, enemies, models, textures, levels, story lines, music, and game modes. Mods are made by the general public or a developer and can be entirely new games in themselves, but mods are not stand-alone software and require the user to have the original release in order to run. Mod or modification is a term generally applied to personal computer games (PC games), especially first-person shooters, role-playing games and real-time strategy games.
