User modification, or modding of games in the open-world sandbox Grand Theft Auto series is a popular trend in the PC gaming community. These unofficial modifications are made by altering gameplay logic and asset files within a user's game installation, and can drastically change the gameplay experience: from replacing the player's character model with a fire breathing cat, to spawning zombies throughout the map. Frequently created by anonymous 'modders', modifications are presented in the form of downloadable files or archives. Third-party software has been indispensable for building Grand Theft Auto mods, due to the lack of official editing tools from the developer, Rockstar Games.