UNLICENSED GAME This game is an unlicensed version of Microsoft Flight Simulator X. User Summary Prepar3D is Lockheed Martin's continuation of the Microsoft Flight Simulator family of games. It is based on the Microsoft ESP simulator, which is the commercial-user version of Microsoft Flight Simulator X. While Prepar3D is fully licensed and authorized by Microsoft, the limitations of that license prevent it being sold for "personal computer entertainment". It is however seen by many members of the flight sim community as the natural continuation of the series, and the licensing constraints that it is sold under are not seen as a limitation to the end user. v4 is the most substantial update to the core flight simulator engine to date, marking the transition from a 32-bit to 64-bit binary, making it far more expandable through third party add-ons than previous versions of Prepar3D, or Microsoft Flight Simulator before it. Also of note is that v4 integrates native virtual reality support (Oculus Rift & HTC Vive). v4 also includes additional aircraft created in-house and by third party developers: F-16A F-16AM F-16C Lockheed Electra 10A Milviz P-38L While retaining the same name as its predecessors, it is sold as a separate product, much like an annual edition of a sports video game franchise.