For the first time ever, players can experience a full life simulation on a handheld with Nintendo DS and 3DS. However, Sims are unable to age, WooHoo, or have children. The neighborhood in the game is Beacon Bay, and many familiar Sims and/or relatives, such as Malcolm Landgraab and Alexander Goth, appear.
- It features a new Karma system. 
- "Create any Sim you can imagine – give them unique personalities! Fine-tune your Sims’ appearances and personalities. Make them evil, romantic, paranoid, kleptomaniacs, or a mix of something completely different."
- "Unlock all-new Karma Powers. Wield the ultimate control over your Sims giving them wealth, beauty, and love—or take it all away with the click of a button."
- "Control your Sims’ destinies – Choose whether or not to fulfill your Sims’ destinies by making their wishes come true—or letting their dreams die. Will your Sims be rock stars, world leaders, or expert thieves? It’s up to you."
- Complete challenges to unlock additional items, new buildings and landmarks.
- Players can "sculpt" Sims using the stylus.
The trailer for The Sims 3 for Nintendo DS was released on October 7, 2010. It shows many of the original features of The Sims 3, such as cycling around town and changing Sims' appearance. It also shows the newly-added features, such as 'Karma Powers'. It also shows that, unlike previous games, building and customization has been greatly expanded.
- The idea of Karma is taken from the Hindu religion. However, the Western interpretation of the term more accurately describes the Karma system in the game.
- Due to the presence of an adult Alexander Goth, it is presumable that the game takes place about 20-25 years after The Sims 2.