Firstly, what Mac do you have? Please post the following info - http://answers.ea.com/t5/The-Sims-Mac/READ-FIRST-Sims-4-Mac-Help-Guides-and-Troubleshooting/m-p/4612396/highlight/true#M162
Secondly, are you running any CC/Mods? Have you tried running the game without them and did it make a difference?
Thirdly, have you moved your Sims 3 folder from Documents > Electronic Arts out onto your desktop and tried playing? Did it work?
I have a MacBook Pro (Retina, 13-inch Late 2013)
Processor: 2.4 GHz Intel Core i5
Memory: 8 GB 1600 MHz DDR3
Graphics: Intel Iris 1536 MB
I used to have tons of CC/Mods and Sims 3 ran fine with Yosemite, but not with El Capitan. I removed all the CC/Mods and I'm still having the same problem.
Yes, I believe earlier I tried moving the folder to desktop and it did not work.
If you read this thread specifically for owners of 2013 and onwards Macs, you'll find your Mac listed as one of the ones that is incompatible with Sims 3 due to the Intel Iris graphics not being supported- http://answers.ea.com/t5/The-Sims-Mac/CURRENT-ISSUE-The-Sims-3-Issues-playing-on-newer-post-2013-Macs/m-p/4935394#U4935394
You were lucky that your game played pre El Capitan but evidently something changed from Yosemite to El Capitan.
In the linked thread above you will find instructions on how to edit your graphics card files so you should be able to play again.
I followed all the instructions and I am still having the same problem. My best bet would probably be to uninstall El Capitan, but I can't do that because I don't have Time Machine. Hopefully I can figure out another way to make my game work @Bluebellflora
