I am creating a sci-fi world for tabletop RPG and I have trouble with one thing and that is artificial gravity. What I need is to come up with some ideas for in-world reasonable explanation for the technology of artificial gravity used in ships or stations, which I can provide to my players, but I have a few limitations and restrictions on that technology so it won't break some other things:
1. It has to be believable. I have curious players, so it cannot be just "it works" explanation. I know currently artificial gravity is only possible through centrifugal force or constant acceleration, but this is not what I am looking for. It does not have to be scientifically plausible (it is not hard sci-fi), but it should have some reasonable and interesting explanation (with only some handwavium elements like exotic matter or similar).
2. It cannot allow for FTL travel. Many interesting artificial gravity explanations in sci-fi are able to manipulate space-time and this also allows for the means of FTL travel (warp drive, mass effect). This is not desirable in this world. FTL in this world is present, but it is very rare and not understood (not human) piece of technology (which should not be the case for artificial gravity).
3. Other, less obvious, uses of the technology should be addressed. Sometimes technology for artificial gravity can create a lot of potential in other areas, which may create some gaps in the world (weapons, shields, industry, propulsion). I am not against some useful applications, but I would like them being acknowledged and it should not be something very ground-breaking.
4. The technology has to be reasonable available. As I said before, the technology can use some exotic matter or elements, but it must reasonable available in the world, where spaceship is expensive, so not everyone can afford one, but it is not something unusual (maybe like private airplane/helicopter in our world).
I already tried to go through this and similar forums, but I wasn't able to find something which would work for me, so I would like to kindly ask for your ideas and suggestions.