The player begins as an aspiring detective alongside their friend Buddy in the Wii version. Upon completing a case regarding a dog and its true owner, the player is approached by a special agent from the Sim Protection Agency (S.P.A) who informs the player that their application is approved and they are hired as a junior agent.[3] The special agent notifies the player that the agency is onto the man from the dog case (whose name is revealed to be Morcubus) believing he has a grand villainous plan.[4] After solving the cases on main street, the player is promoted to a special agent and is given access to the first S.P.A headquarters located in the town.[3] Inside the headquarters, there are five floors, four which can be decorated with furniture the player earns in the game.[5] As part of their workload from S.P.A, the player is also able to hire other citizens as junior agents, whose purpose is to solve dispatch missions.[3] Each case which the player investigates involve several minigames which are analyzing chemicals, hacking, lock picking and repairing machines.[4][5] The player wields several tools throughout the game which are a wrench used to salvage spare parts, a magnifying glass which is used to track footsteps and a crowbar used to pry objects open.[6] As the game progresses, each tool gets a technological update.[5]
In the DS version, the player works as an undercover agent who learns from the town's mayor that a thief who goes by "V" is planning to steal the town's secret treasure and has to catch him before he obtains it.[7][8] Throughout the game, the player must complete minigames, side missions, travel to different locations and interact with villagers to determine V's whereabouts.[8][9] Completing the minigames rewards the player with Simoleons, the in-game currency of the Sims universe, which can be used to purchase decorations.[7] Additionally, the collection of essences from the previous MySims games returns and the player can decorate the town, their house or headquarters.[8]
By contrast, in the Wii version, the player instead solves a series of mysteries which are all connected to Morcubus and his organisation Morcucorp. These cases take them through a variety of new regions including a mountain range, an industrial district, a bayou mansion, a beachside boardwalk and finally an Aztec-themed temple. By completing each quest, they earn new junior agents, and decorations to increase the agents' statistics (there is no Simoleon currency and decorations are not purchasable). By opening treasure chests, examining (e.g.) hedges and trash cans and more, the player can find decorations, wearable clothing cosmetics, and paints for their headquarters.
