Turn 10 studio head, Dan Greenwalt confirmed in an Interview with IGN that Forza 5 will in fact be playable offline. The catch is however that it will require a one-time connection to Xbox Live to download the necessary data in order to make it do so.

The one-time connection will download the necessary data for Drivsatars and other content like tracks and cars. Part of the download is apparently due to the change in Microsoft policy, while some of the content is due to the production schedule.

Still to really take full advantage of the features in Forza 5, including all of the cloud based features, a connection to the Internet gives players the best experience.

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