Sometimes the download or installation fails. This can be for a variety of factors, including your internet connection dropping out during the download. Sometimes this can result in an awkward situation in which Origin acts as though the game is installed correctly. This means you can’t play the game, but nor will Origin let you re-download it. You cannot easily “uninstall” the game, because of course it isn’t there.
First thing to do is to go into Applications on your Mac and look in the folder called “The Sims 3”. This is the location from which your game actually launches (as opposed to a similarly named folder within Documents, which is where your saves and other data are stored). In the folder in Applications you will see the shortcut icons for the base game as well as any expansions or stuff packs installed. If you can see the icon for the game that has failed to properly download from Origin, try right clicking on it and this should give you the option to show the original file. You can move the original files to the trash from there. This may allow you to commence a re-download from Origin. (Many thanks go to Tremayne from TS3 Mac forum for this suggestion.)
Before trying to download again from Origin, remove the Origin client and reinstall it.
If this does not work, or if the icon is missing from the “The Sims 3” folder in Applications, then you may need to completely uninstall and reinstall:
http://bluebellflora.com/the-sims-3-on-a-mac/how-to-do-a-clean-uninstall-and-reinstall-on-a-mac/Good luck!
