Any Idea Can Work Spiel & Audience?
Almost any idea can work, it is all about execution. Sure, some ideas may put off certain readers, but if the work is engaging for the reader I'd say you've succeeded.
If you really want to reach wider audiences think about demographics and stuff, who will be reading your story, who will be your target audience? Don't say everyone (generally false) or people like you (too vague).
You certainly can aim for wider audiences, but trying to write for everyone will likely end up with you writing for no one, as your story will be too bland to engage anyone.
Writing for people who share your interests is perfectly fine and something I'd generally expect, but if you are trying to think about who you are writing for you'll want to narrow it down to some more concrete thoughts.
What to Write
Moving on, how many branching stories have you written so far?
If you haven't written any yet, I'd just advise picking a random idea and pushing yourself to accomplish it. It can even just end up as a learning experience. I mention this because too many people have ideas, but then struggle with the actual act of writing, however if you never write you're not going to get better (if you ask me), so write!
On the other hand, especially considering you have a site, it is possible you have written branching stories before, in which case I'd say either write in the same vein as your other works, or work on filling in gaps (and thus going for more variety).
Obviously, you'll never be locked into anything, but readers can come to associate you with a certain type of story, even if you can change your approach later. But this is my advice if you're struggling with picking an idea at the moment, as figuring out some sort of approach can be good, since it can provide guidance.
Alternatively, I should mention, you can be one of those crazies who works on multiple things at once, bouncing between ideas as inspiration strikes. This can be tricky to pull off which is why I don't generally recommend it, but as I'd say writing is about finding what works for you, I figure I might as well mention it. With that said, do be careful of just bouncing around constantly without returning to finish ideas, as that is a pretty bad limbo to get stuck in if you actually wish to finish something.
What I Want to See
Quality and consistent writing, good flow and pacing, well handled branching (whatever the style), compelling characters/plot/world (with more weight given to whatever is more relevant to the work), and perhaps, just maybe, some sort of artistic vision/intent (even if that intent is just to write something fun/cool). Some sort of themes might be nice, but I shouldn't get ahead of myself.
But this is all a bit misleading, because my expectations do shift depending on what I'm reading, and honestly, I'm pretty bad at picking up on stuff like symbolism and the meaning/message behind works, so I should hardly be mentioning that I want themes when I probably wouldn't even notice them.
As such, what I truly want is... proofread stories, as that'll increase the likelihood that they are what I truly want. Well-written shit. So go forth and put some effort into what you are creating, and enjoy yourself!
TL;DR
Just write something, anything, but if you've written stories before maybe write something similar to something you wrote before (i.e. more fantasy). Ultimately, just put in some care and effort, almost certainly proofread, and above all, write.
