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Once dropped into the Sims world, gameplay works as usual, but with a few changes and new features. Players will be able to participate in new activities with their pet Sims, such as traversing pet park obstacle courses, visiting veterinarians, and playing games like fetch. For the 3DS, the control method for selecting objects in the world has turned away from the stylus in favor of the 3DS’s new slide pad, allowing for greater system stability while using the 3DS’s 3D effects. The slide pad now controls a cursor that is used to highlight objects. Other options such as managing inventory, customizing Sims, and using Karma powers is handled using the touch screen menus. Sims 3 Pets also works with the 3DS Street Pass system which allows Sims to be downloaded via the Sims Exchange.
Source: Sims Nieuws