When I at home with no internet I can't play Sims 3.
When you start the game it will try to log you in to the server. You have to wait for the connection to time out and you should get a screen asking if you want to continue w/o a connection.
Check out our Sims forums for tutorials and all things Sims.
Try these steps first to clear up any problems you may have when connecting to an EA game.
We'll make sure it's you by sending you a code for your trusted devices.