Saw a couple of other comments about the program, and I just want to say that it's safe to use. Windows freaks out about it, but it freaks about any program where it doesn't recognize the publisher. Looking at task manager when it runs doesn't show anything untoward. No unexplained resource usage or similarly named windows apps taking more resources than they need. Additionally, Malwarebytes says it's clean, and that's good enough for me.
That said, this is a wonderful tool that's made fleshing out my stories a lot easier compared to other world building and writing tools. I have a few stories going at once that take place in the same town, and with the graph I get to see clearly how everything relates together. A nice touch is the option to exclude certain objects from the graph so they don't clutter it up. Plus, with everything interlinking through keywords, if I'm unsure about a detail I can't quite remember, it's just a click away. In say scrivener, I'd have to dig through my file sections, since I end up way more cluttered in it than I do in nebulous.
I will say, it is a smidge clunky feeling at first, since it took a moment to get used to creating objects to act as the over arching categories to nest new objects inside. Once you get used to that though, working in it is a breeze. It's making writing for my game easier since the way I use it works well with how I think, easily hopping from one section to the next, adding bits and pieces as I go. It's like super organized sticky notes.
My only request (if it isn't in the program already) is to have the writing fields be in dark mode too. Hurts my eyes a bit when I have to edit or add objects, and it's a flash of white from the text fields when I open them up. I know there's an option for changing themes in nebulous, so if there's an option for that to make the text field dark, I haven't found it yet. ; w ;