The Mac App Store slated to open in January 2011 will exclude in app purchases and promo codes. The store will also disallow development for the Game Center. As with the current App Store, developers will also not have the ability to post freemium apps.
Apple demands that apps be complete retail versions with demos and trailers to be provided on developers’ websites. The lack of the in app purchase option means games cannot be offered free with add-ons or upgrades to be purchased separately. Furthermore, the exclusion of Game Center development excludes the use of the Apple social networking game experience.
The combination of limitations will hit independent developers the hardest. Devs with scarce resources will have to have a fully realized game before release and a website to promote it. Without promo codes and social networking, it will be harder to promote games and generate buzz. Developers will likely release versions for both the Mac App store and the iDevice App Store, with the latter used to promote the app for the Mac. Hopefully future developments like app sharing will come to fruition giving devs other avenues for promotion.