@seaboyerj There are several causes of the unknown error message on a mac, depending on your graphics card and which packs you have installed. Bluebellflora has written a very helpful guide to installing TS3 in mac OS, with walkthroughs for the various problems that prevent the game from launching.
https://answers.ea.com/t5/The-Sims-Mac/READ-FIRST-Sims-3-Mac-Help-Guides-and-Troubleshooting/m-p/698...
If you've already installed several packs, you may want to go about the process backwards instead of starting with the base game only (step 1). But do make sure that you run the Super Patch linked in the post, as the launcher can't handle patching the entire game.
If you complete steps four and five and your game still won't launch, you may need to edit the .sgr files (step 2). If you're not comfortable doing this yourself, please provide your mac's specs, along with your graphics card's device ID, and someone can help you with the process. Here's how to find the relevant information:
https://bluebellflora.com/2018/07/24/sims-3-mac-players-i-need-your-help/#Information
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I don't work for EA. I'm just trying to help fellow players with their games.
