GearCity implements a flexible modding system that allows you to substitute core game files without overwriting them. There are two categories of modifications to the game: Maps and Mods. Map files include Artwork, City, AI, and Turn Event information and are used in conjunction with core game files. Mod files include every other type of file except map artwork. Files loaded with a Mod file will generally override core game files and map files, the exception to this is artwork. With Mod artwork, the Mod files will only override the core game files if the file names overlap.