Ask HN: Physic-accurate space flight simulator?

What are the options in terms of space flight simulation with reasonably accurate physics? Looking to simulate and study lunar missions (NASA Artemis Program).

This requires being able to load 3D CAD models of spacecraft and landers. It also requires moon data with terrain height maps.

So far this seems to be one of the options (not sure it can do all of the above):

http://orbit.medphys.ucl.ac.uk/index.html