I also don't like the idea that something like that can be killed, or die or have some sort of ramification in the setting.
See to me, that's part of what makes gods awesome, and different from just some kind of big, powerful dude.
What if killing the god of death means nobody dies anymore? Or what if killing them changes nothing? Maybe it will just drive all their priests mad, or stop all their prayers from allownig the dead to rest in peace?
That's the kind of ramifications a PC would ponder when entering a conflict with such an entity, which is not going to happen when they're killing a Really Big Giant or an evil space whale or something.
3) I dunno. I can't quite imagine a religion that would catch on with billions of people from thousands of planets, where it's a jumble of peoples and culture. What single idea could feasibly unite them into a coherent or incoherent dogma?
Literally, the only thing that could bring them together- comunication. All those planets, how do they comunicate? What if they, or may of them, saw that act itself as sacred?
I mean




, imagine if we were able to comunicate with thousands of other worlds, with travel a much harder and less common event. I think a lot of people would look at the galactic comunity that resulted as the ultimate achievement of sentient life.
And what if this comunication grew increasingly difficult, or costly? What if these many comunities went through a period of exchange and sharing of information and ideas, art, science, history, stories of all kinds, entertainment- a golden age- but then the cosmos changed, and that comunications network was put in peril?
Sure, some people might want to close their eyes to the cosmos, but a lot of people on all sorts of worlds, could see that comunication as sacred, and see the work to overcome barriers to comunication, logistical, cultural, and political, as a sacred work.
Such a movement could be called The Word, or The Dialogue. Outsiders might view it with suspicion, especially in a setting with virtual technology, cybernetic mental comunication, and other ides that could lead to fears of a 'hive mind' or some kind of control being established.
Radicals in the movement could even push for such an approach, and who's to know- the conspiracy nuts might be right, and the whole thing might just be a front for an effort at galactic mind control. The culprit? A rogue ai? An unknown alien race from beyond the rim? Or perhaps the galaxy's first spontaniously generated higher inteligence?
Are you
sure you don't want to put a god in your setting?