Necronautilus is a gorgeous game I enjoy more and more every time I dig into it. But... is it NSR?
I have never played another game like Necronautilus, and that's a shame. If you like wordplay, thinking about the relationship between memory and reality, and psychedelic fantasy in space, then you should check out this game.
Troika! is a science fantasy OSR game with some really cool ideas in it. Several of them you could pull out and put in your own game even if you don't play Troika! per se. Here are four of them.