Bushikatagi

This game basically does exist already. Search for Orbiter 2010, it's a free game being developed by one guy. The next update should be coming sometime this year which is going to include high resolution textures and height maps for most planets. The detail of the physics simulation is pretty intense including things like non-spherical gravity sources, reentry heating, solar pressure, etc. The default game comes with a couple different craft but the internal systems aren't modeled in great detail as some of them are near-future fictional craft. Mostly you just get some MFDs. There are many addons though, some of which model many of the systems and have clickable cockpits. There is a mod to do some of the Apollo missions which includes everything from take off to landing in as much detail as I imagine anyone could need.

Maybe because that's a $100 textbook and he's just asking a simple question. Besides the answer is yes, a HOJ missile can do proportional navigation just like an IR missile can. An IR missile does navigation by knowing the bearing of the target (technically the derivative of the bearing for PN navigation) and guessing the closing speed. The same is possible for a missile fired on a jamming target as the bearing is known (it has to be or else the missile wouldn't be able to follow a pure pursuit either).