There are no plans to introduce a SDK to the Steam edition at this time. If you wish to use the SDK it remains available in the boxed edition of FSX and all functionality will continue to work as it did prior to the release of FSX: Steam Edition.
FSX DELUXE OR GOLD SIMULATOR
FSX: Steam Edition does not include a developer SDK and the focus for this release is to provide players with a stable standalone simulator which utilises the advantages of the Steam platform. Microsoft has now issued us with clarification on this matter. We are sorry for any frustration this may have caused. This has meant that we have been unable to address your enquiry as quickly as we would like. Implementation of the SDK currently falls outside of our agreement with Microsoft and therefore we have brought your enquiry to their attention so that we can best provide you with the information that you require. We know that the SDK is highly important to the FSX developer community and that the current situation regarding its use with FSX: Steam Edition has not been made clear. Although we have optimised FSX: Steam Edition for use on Steam, in accordance with our licencing agreement with Microsoft we are not at liberty to make significant functionality changes to the simulator. Meanwhile, Dovetail Games is acting as a publisher for Microsoft and is only licenced to modify the simulator in order to make it Steam compatible. Microsoft remains the developer of FSX and is solely responsible for implementation of any features or content. I have now heard back for you regarding the SDKs.
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