Yes, here’s the deal. It’s a bad news/good news situation. We couldn’t make online play work directly in the Mac App Store version of the game consistent with Apple’s requirements, at least not in time for the Mac App Store launch. That’s why the Mac App Store version is USD6 less expensive.
BUT the good news is that we have designed a workaround that should let Mac App Store purchasers upgrade their game to include all of the features of the regular versions, including challenges, the race expansion packs, and the campaign. We have submitted that update to Apple for review, and as soon as it’s available on the Mac App Store (assuming it gets approved), Mac App Store players will be able to pay the difference in price through our website and get full features in their game. We’re just waiting for Apple’s approval and this situation should be remedied.