I had my second dream last night where I suddenly found myself in a world where our civilisation was gone. It just wasn’t there anymore, buildings were missing, everything… As if I had been teleported into a different time. Exactly the same place, but another time. It was so galling and depressing, and prostrate… 
I had no idea whether it was the stone age or instead I was far into the future. I had no idea what I should do now, just so completely powerless…
In my other dream I suddenly died and the other thing I know I was in the same place but Earth was covered in water (the surface might have been somewhere way above) and apparently I was not human anymore. I was still moving to the same direction as I had been before dying. There were now only ruins, what was left of human built structures (e.g. the bridge I was on), though again I had no sense of time, whether it was year 3000 or 10000 A.D. I knew one thing though - I had a mission to restore civilisation on Earth.
So anyway, have any of you had dreams like that, where our civilisation was either not shaped yet or has vanished?
I sometimes fantisize that I am the only human in the world. Everything is just nature. I’d like a dream like that. Especially a lucid one.
The second one though, Waterworld type scenario sounds a little less fun. I like land.
As far a civilization in dreams… I’ve had a lot, and I mean a LOT of normal dreams about dying in nuclear holocausts. Like, my friends and I are off doing something important (that, in retrospect, isn’t that important) when we suddenly “know,” perhaps by a siren or a news broadcast, that a nuclear bomb had been launched at our town. We always try to run away, but the dream always ends the same: we’re clutching to trees, poles, anything really and hoping against hope we don’t die.
And of course, we and all of civilization always die in the end.
I don’t personally believe nukes will be the death of us all, but try convincing my sub-c! 
I occasionally get some NDs where I’m either a survivor in a post-apocalyptic world, or where I died, and I’m viewing the aftermath in a very Hollywood-like manner (occasionally I’m even doing a voice-over type thing and describing the carnage). It’s weird getting up the next morning, after one of those.
I once dreamt I died in a nuclear explosion. Other than that, I recall a foggy dream in which two close-passing planets were at war, and devastated each other’s civilizations. As for being the lone survivor with civilization gone, I don’t think I’ve experienced that.