Hello,
We do not have enough information at this point to say whether you would need to purchase the game again for Mac.
The only way to possibly play The Sims 4 on a Mac at the moment is to setup Bootcamp or a Parallels desktop with a full license of Windows 7 or 8 (however this is yet to be confirmed), but this can be hard to setup
If you have anymore questions about a potential Mac version of The Sims 4, please post here:
http://answers.ea.com/t5/The-Sims-4/INFO-Sims-4-Currently-NOT-for-Mac-Ask-questions-here/m-p/2957168...
I hope this helps and keep simming,
Cody
