User Summary
Microsoft Flight Simulator X: Steam Edition is the re-release of the original Microsoft Flight Simulator X and all of its service packs as well as the Acceleration expansion pack.
This new version incorporates Steam services to enable multiplayer support, replacing the defunct and no longer operating GameSpy services of past editions, as well as updates to improve compatibility and performance on more recent versions of Windows. It also supports DLC that is published exclusively (or sometimes timed exclusives) via Steam.
It is updated and published by Dovetail Games under license from Microsoft.