From Wikipedia:
The Wii version of MySims Kingdom takes a departure from The Sims franchise and begins with a character moving into a run-down kingdom with a king desperate to bring happiness back. The player's job is to rebuild or remodel, homes for the characters using scrolls given to them by the islanders. Players must collect essences to unlock these scrolls and gain new items from them, then you collect "mana" used to create furniture and such, and in return are given essences, scrolls, and outfits for their Sim. As the kingdom's happiness increases, new islands are unlocked. To unlock more places, you have to run errands for the new island until your kingdom is a five star kingdom. After you reach the third star and a full night-day cycle has finished on the island, you get to do a second set of missions for all the characters.
You can also interact with citizens by doing certain things with them such as having a picnic. You can also customize your character using the outfits you can obtain as a reward for performing certain tasks. Some items in the game are interactive such as televisions, stoves, computers, videogames etc. Unlike other games in The Sims franchise, your Sim does not have needs or wants, although eating and sleep is optional.
In the Nintendo Wii version of MySims, the Nunchuk is used for direct movement and the Wii Remote used for object moving and building. You can also use the Wii Remote to go fishing at the fishing spot located around every island. You can shake the Wii Remote to chop down trees or go mining to gain different essences.