Well, I've been working on this about 1.5 year ago.
First, because I got bored of standard FS2 flight model, it started to looked too arcade after I played BTRL. But I still like the FS universe, so the plan was to create a bit more realistic gameplay. After that I came up with the idea of creating a brand new campaign for this mod. I had huge plans for it (like a completely non-linear campaign, unpredictable missions etc.) but it ended up on one camp. mission and two others to test the gameplay. Anyway, I stopped the development at that point and resumed about half yr later. This time with the idea of converting original Freespace 2 campaign into this. But I got bored after finishing half of the missions and stop the dev again. But I still think it's a good project, so I've came back to it.
Perhaps I'll even release a demo. I'm already thinking about it. And this vid shows part of one of the two missions that will be included. This is also the mission that was supposed to start my campaign, which was all about Battle for Deneb (the one with NTF). Here you can see an attempt to take over Capella - Deneb jump node. But more about this mission in demo.
Anyway, it's hard for me to point out all changes, cause I made really lots of them (so much, that after playing only this mod, flying standard FS was really strange to me). But here's a list of things I remember:
1. All fighters are very fast and much more maneuverable.
2. All fighters have the ability to move in every direction as well as glide.
3. Secondaries are stronger and harder to avoid.
4. All fighters now have much fewer missiles with more weapon banks restrictions.
5. The AI is a bit more challenging.
6. There are some new sounds, like Orion's engine.
7. The overall difficulty level has increased. Some missions are much harder than in standard FS, but there are also some that's easier (espesially bomber ones, but that's another story)
8. More emphasis on commanding your wings (in later missions ofc.)
9. Every mission have new background including skybox from FS1 and new nebulas. And here I have a request. About year or two ago someone has released a pack of backgrounds for the most of systems. I used them in my mod (for private usage), but can't remember who was that, so I could ask his permission to include them in the release version?
10. And more things that I cannot remember...
Still have no name for it, so if you got any good ideas I'd be happy to use one of them.
And BTW, don't expect for the demo to be released soon. I got lots of other work (I'm making a fan battletech movie

) and some RL problems, so I can't spend much time on this one.