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Some features will require developer support so don’t expect a fully featured look until public release. Other features are just lacking development from Apple still like controller support for navigating the app and not just launching it.

Library works fine for me. Play together appears but I’ve not dug into it as I don’t really play Game Center multiplayer games on Mac.
 
For some reason, Games cannot connect. The App Store is doing fine.
I signed out of the App Store, and Games prompted me to log in. I did, the App Store reconnected, but Games is still not connecting.
 
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