The game puts players in charge of redeveloping a town that has become run down because a resident who had the power to use essences moved away. Through creative building and design elements, players will take over the new role as a government leader to improve the town, which attracts new residents, who subsequently need homes built for them. Customization is a large element of the game, including houses, furniture and outfits.
Apart from creating a custom Mii-like character, players may also modify their houses and build furniture and appliances using a selection of building blocks. This gives the player more building options, allowing them to create objects by using blueprints, a change from the usual virtual catalog found in The Sims. There are 80 characters with whom the player may interact in the Wii version (30 characters in the Nintendo DS version), such as a mad scientist, a magician, a librarian, a pizza chef, and a martial arts teacher. Some of these characters may ask the player to build things for them. As with previous Sims games, meeting people and forming relationships is a major gameplay focus, but unlike The Sims games, the characters do not have to fulfil needs such as hunger and sleep. Becoming a Sim's best friend will earn the player either a special blueprint not available anywhere else in the game, or a style of clothing for their wardrobe. Players can also earn blueprints by performing tasks for Commercial Sims (Sims who have their own businesses). Typically this involves building around 5-10 items for Sims, depending on the Star Level (the 1-5 level) of the player's town and the essences they have access to.
A feature new to MySims is "Essences". They can be found in various locations in town or by interacting with Sims or objects. Essences are used for a number of things including paint for the walls of houses, construction of items, as well as decoration.
The minigames in the DS Version include racquetball, paragliding, Scuba diving and more.