Other times, a mod is an outrageous yet fun implementation that makes the game more enjoyable. Oftentimes, mods are in line with what the community wants, and in some instances, are even more effective than updates implemented by Maxis. A mod - as the name suggests - is a modification to the game created by a member of the community. If you’re here, you probably already know what a mod is, but for those getting into them for the first time, let’s go through what a mod is. The Sims celebrates its 20th anniversary, shows no sign of slowing down.