File created by The Sims 3, a simulation program where you create and manage the lives of simulated persons, or "Sims;" contains corrupt game save data that was not saved properly and cannot be loaded.
If you have a SIMS3.BAD file, you can restore the game from your .SIMS3.BACKUP file.
Copy the .SIMS3 (if you have one) and SIMS3.BACKUP files and paste them into another folder for backup purposes just in case you make an error.
Go back to your "Saves" folder and delete the SIMS3.BAD and SIMS3 files that are corrupt and delete it.
Remove the ".BACKUP" from your SIMS3.BACKUP file so that it looks exactly like the corrupt SIMS3.BAD file you just deleted.
You are now able to load your game from the game menu.
Common SIMS3.BAD Filenames:
[name of your game].sims3.bad - The filename created when you save your Sims 3 game but fails to save properly.