Q:

Sugar-coating a niche genre

I have written one novel, which I believe to be in the steampunk genre. The main plot revolves around a two adventurous women entering in possession of a fabled machine, and using it to chase the mysterious villain, who seeks revenge on the world (and who, incidentally, just happen to always be one step ahead). 
Despite initial skepticism towards the genre, my beta readers have found the whole story rather entertaining and engaging, and were very willing to submit themselves to a few rounds of reviews. 
I wrote this novel for my mother, who loves reading. I printed it and handed it with a ribbon. While very pleased with the gift, the issue is that she seems very reluctant to engage reading beyond the title. I tried to provide a synopsis, like the one in the opening of this question, but it backfired. I suspect that the issue is again the initial skepticism towards a niche genre like steampunk.
Given that I cannot take back the information I already provided about this novel, how can I better promote my work, and maybe better illustrate the genre, to convince a non-fiction reader to venture through at least part of the book? So far, I have not insisted, worrying that she may pretend to browse a few pages, just to please me, and set it aside for good.

A:

I think of Steampunk as being science fiction (with some fantasy elements) based in the Victorian era. 
The term "punk" might turn off some readers.  Simply being unfamiliar with it might be the turn off for others.  So better to explain it using terms the reader will understand (by all means market the book with the niche term Steampunk to reach the readers who want that, but that's not what this question is about).
In your case, you're not really marketing your book, you're selling it.  To one particular person.  The person whose view of this book is most important to you (since you wrote it for her).  So focus on her.  What books does she enjoy?  Find something similar and make your case.  (This works for larger marketing too where you'd tie the book into similar but better known genres/styles/etc.)
In the end, I suspect you're going to have to fall back on guilt.  I wrote it for you, please just give a try.  That is the best marketing available for family members.

A:

I have no advice about your mom. However, I notice that within the question you signal the story is not to your own taste, that beta readers held their noses but liked it ok, and that you are unsure what genre it might be and even if you did know it is obviously "just a niche".
This is not selling your work.
In order to make this a general interest question, I suggest that you consider a few angles on how to describe the story. If you feel the setting is so obscure that it isn't a selling point, maybe step back to story fundamentals? It's "an adventure about 2 smart women", in a "Victorian-inspired world" where "magic and technology blur", who use "a fabled machine to hunt a mysterious villain" (this part I quite like). 
You can invoke the familiar, "like Sherlock Holmes, but with women and touches of sci-fi" and you can extrapolate the situation: "Complications ensue when they begin to use a legendary device to track a criminal." Say what the story is about, it's conflict and mystery, rather than its setting. 
In otherwords, if steampunk sounds iffy, don't use that word. If you have your doubts, don't say them upfront. The genre is actually sci-fi/adventure/mystery (I assume). Steampunk is probably more the style than the genre – but you would know better what your own story's fundamentals are. Sell the story, not the tropes and decor. Writing a blurb is a whole marketing exercise, I'm just trying to point out how many times you've under-sold the story in your question.

For a while I dismissively called one of my projects "dumb ghost hunters who solve occult crimes" because frankly, I thought the "genre" (whatever it was) was beneath me. The stories would be easy to write because they were pastiche of horror and mystery tropes. I didn't actually feel the idea was "bad", but it was a project I felt I could have fun with – more self-deprecating than insult to the genre. I didn't want to take myself too seriously.
Well, that joke is at my expense because that project is getting more focus now, and as it evolves of course it naturally becomes less "dumb" to me personally. But also I now feel it has some substance as I work out the details and the tone. No one ever asks me about this project, instead they ask about a different project, my "opus" that I bragged about that was going to be highbrow space opera with amazing characters and a totally original setting. Get the idea? I probably sabotaged myself by signaling that one project was aspiring to greatness, and the other was indulging in popular tropes I wasn't too sure about.

