X-Plane is incredibly extensible. You can simulate new aircraft, make 3-D models, or even change the functionality of the program in drastic ways.
X-Plane 11.20b1 is the first beta that includes non-VR improvements. Full release notes are here, but a non-comprehensive short list of the most exciting additions is:
Formation flying: this beta includes Jörg’s new code to improve network sync, both for external visuals and multiplayer/formation-flying. Read More