Some of you might remember this. We wrapped work on this back in November. The thing is, no one suspected at the time that the entire Constellation program would be scrapped. Since it looks like it’s being cancelled in the next budget though, I thought this would be a good time to dig this up again. One last hurrah and all 
So here it is. This might be the closest you, me, or any human, will ever get to actually driving the Lunar Electric Rover as it currently exists, on the moon.
As far as I know, this is the only actual simulator for the Constellation missions that was ever finished. And it was done in Unity3D.
Mac and PC, of course.
http://www.frassanito.com/RoverSIM/
Oh, and Frassanito and Associates also took the secret candy wrapper off this site, which has a TON of visualizations for various parts of the Constellation program.
http://constellationprogram.com/startpage/
There’s some cool stuff on there. I only worked with them on the Rover simulator, though.
-Chilton