Mac client?

[ArkhamNative]

I'm not 100% clear on the details, but Apple usually requires ports to go through an approval process.
And it's very rare you'll see a big name port not on Mac App.

If developers go through Apple's App Stores, there are rules, definitely, and an approval process, and Apple takes a percentage (just like stores like Best Buy, Amazon and Steam do), but none of this would keep most games out.

But Mac software doesn't have to use the Apple store. MMOs like WoW and probably TESO sell their stuff separately. The reason most games do go through the app store is they already follow all the rules and the store has a huge customer base. But what I said above is true. If devs don't use the App store, Apple gets no say and no cut.