Oh , you mean modification.
A mod (short for “modification”) is an alteration by players or fans of a video game that changes one or more aspects of a video game, such as how it looks or behaves. Mods may range from small changes and tweaks to complete overhauls, and can extend the replay value and interest of the game.
https://en.wikipedia.org/wiki/Mod_%28video_gaming%29
Game mods can do a variety of things. Some people like cheat codes, other simply want it to look different or have altered mechnics which are not cheats.