Game developers are not 'normal users'.

If I'm working as part of a team, we'll have internal systems for collaboration, usually including a wiki.

If I'm working alone... then maybe I'd find a use for a standalone tool like this, although most likely I'd just use OpenOffice Writer. But if the tool was comprehensive enough in terms of search, cross-referencing, indexing, etc., it could be useful. I still wouldn't want an explicit tree structure though.

One thing to bear in mind is that game development documents are communication tools. Is this tool for communicating with the writer, ie. as a memory aid? Or is it to communicate with others, ie. to provide documents to work from? If the latter, what benefits does it offer, given that it will just export to a file similar to that created in a mainstream app?

What would you want rather than a tree structure then to keep it organized and/or categorised?

It's a bit of both. Nothing stops more members on the team using the tool to view the lore structure as intended by the program. Exporting to PDF or similar is for convenience and if that's how the writer uses the program, it would simply serve as Memory Aid.

There's a program out there very much like this on Steam, though its price tag is a deterrent for most of us who are on a shoestring budget for things we can readily make do without; the program is named articy: draft SE by nevigo.

http://www.nevigo.com/?id=47

Steam has demo videos of it; so if you'd still like to work on it as a free alternative, I doubt they'd mind much if you used their demonstration as inspiration (otherwise, we'd all be prohibitively in debt to the giants that came before us; upon the shoulders of which we so brazenly stand, using their concepts to strengthen our own).

Yeah I know of this program. A guy on another forum suggested if I made a version that costs 5 to 10 dollars or something it'd be a nice market since that program is just so damn expensive.

I am still not really sure whether it should be free or low-cost but another alternative to that program wouldn't be too bad.

Another avenue is releasing the product as a free thing with source material being available to those who want to fiddle around with it themselves while offering your own pre-built addins for a fee. Like how some web theme and javascript sites operate; the base kit is readily available and it's all Javascript or C# or C++, but if the consumer wants to get a package deal that has more functionality, they can pay $5-$20, all based on how much extra functionality there is and how much work you did to implement it.

Ah yes.

So a community edition and a premium edition kind of thing. That could be something.