Open world gameplay
The Sims 3 was the first mainline entry in the series to feature a fully open world. Sims can move freely around the entire neighborhood without triggering loading screens, making it possible to follow them to work, visit community lots, or explore the town in real time. The included world, Sunset Valley, is significantly larger than neighborhoods in previous games and ships with around 25 playable households. A second world called Riverview was made available as a free download.
Traits, moodlets, and lifetime wishes
Instead of the personality point sliders used in earlier games, The Sims 3 assigns traits to each Sim. Adults can have up to five personality traits, which shape their behavior, social interactions, and available lifetime wishes. A moodlet system tracks short-term positive and negative emotional states caused by specific events, surroundings, or shifting needs. Completing a Sim's lifetime wish earns lifetime happiness points that can be spent on special rewards.
Create a Style and customization
The base game added the Create a Style tool, which lets players change the patterns, colors, and materials on clothing, hair, objects, walls, and floors. Styles can be copied between items, giving players fine control over the look of their Sims and homes without needing custom content. Create a Sim also received expanded options for shaping faces and bodies compared to The Sims 2.
Story progression and post-launch support
Non-player households continue to live their lives through an AI-driven story progression system. Sims outside the active household can get married, have children, change jobs, and age up on their own, keeping the neighborhood feeling alive over time. The base game was developed by Maxis and published by Electronic Arts for Windows and Mac OS X, with console versions for PlayStation 3, Xbox 360, and Wii following in 2010. Post-launch updates expanded the game considerably, including patch 1.22 which introduced per-age-stage lifespan sliders and shared memories, and expansion packs such as Generations.