Instructions
Enter Freeplay Mode from the main menu. You'll be prompted with a panel that allows you to choose the Sims as whom you wish to play.
Pick a house that has at least two Sims in it. Each player will have a different, individual Sim to control. The game will begin loading the selected house.
Press the "Start" button on the second controller when the house loads. The screen will split in two, and each player will control a Sim. If there are more than two Sims, Player 1 can control them as well.