There's a simulator, if you want to run it.[1] But it's just a simulator for the computer; there's no spacecraft attached.
There's a mod for Kerbal Space Program which gives it real solar system planets and dimensions. (KSP's world is way undersized so things happen faster.)[2]
There's another mod for Kerbal Space Program to give it real dynamics.[3] (KSP doesn't really do dynamics right; the spacecraft is under the gravitational influence of only one body at a time. This is why there's that sudden trajectory change upon Mun capture.)
Someone should hook all that together and do a moon landing in simulation.
[1] http://svtsim.com/moonjs/agc.html [2] https://www.reddit.com/r/KerbalSpaceProgram/comments/1piaqi/... [3] http://forum.kerbalspaceprogram.com/index.php?/topic/62205-w...
I'm really surprised there isn't a moon landing simulator based on the real code yet.
There's an Orbiter plugin[1] that simulates the rest of the spacecraft. IIRC it can interface with this simulator to get an accurate simulation of the computer.
[1] http://nassp.sourceforge.net/wiki/Main_Page