Apple's next mac OS update will block games not downloaded from the App Store or made by registered developers.
The move is intended to unify the experience of Mac users, and bring more consistency and security to the platform.
OS X Mountain Lion includes a feature called Gatekeeper that prevents software not registered with Apple from running.
The settings can be altered to allow unregistered products, but those who have built up a library of titles available for the Mac through platforms like Steam may not appreciate having to lower their security settings in order to access software they've already paid for.
Users can also increase security by allowing only App Store products to run, and Apple says the system will help prevent malware from taking root.
Developers as well may take offense to Apple making it harder for them to release their products on the new OS, but the Game Center for mac, a feature of the new OS already available on iOS, may compensate for this by opening up a range of social features for implementation in games released through the app store.
OS X Mountain Lion will release this summer as a paid update available through the app store.