Is there some way to describe something that the average person doesn't know about but is still not obscure? Such as a musician who doesn't get much radio play but still has thousands or even millions of fans, or how an independent movie that does well at a festival like Sundance but doesn't get a major release.
(Adjective). Denoting or relating to products, services, or interests that appeal to a small, specialized section of the population:
- other companies in this space had to adapt to being niche players
- a niche show that ran on late-night television
- the video game industry is no longer niche.
Of a subject or knowledge - little known by the layman or in the mainstream of received wisdom or knowledge. (Oxford Dictionary)
One might write, for example, that intellectual property law (patents, trademarks & copyrights) is a recondite subject matter for many lawyers.
In the alternative, I propose the word fringe
adjective, not part of the mainstream. (Oxford Dictionary)
So, one might say, for example, that the little known playwright has had his work performed to fringe audiences Off-Broadway and at fringe gatherings at the Edinburgh Festival.
- Of or denoting a group or movement seeking to explore alternative forms of lifestyle or artistic expression; radical and experimental:
the New York underground art scene
wikipedia: Underground Music
Underground can be applied to many forms of media, in contrast to more specific terms such as
- avant-garde art
- experimental , "experimental jazz"
- alternate , "alt rock"
- independent - the connotation is more about how it is funded than its popularity, but non-mainstream funding usually implies non-mainstream popularity
Cult may be suitable:
[USUALLY AS MODIFIER] A person or thing that is popular or fashionable, especially among a particular section of society:
'a cult film'
- 'It did remarkably well at the box office, and garnered a strong cult following among college-age Americans.'
- 'The company's ads have gained a cult following among advertisers and laymen alike.'
Intended for or likely to be understood by only a small number of people with a specialized knowledge or interest: esoteric philosophical debates - Oxford Dictionary
Differs from niche, which applies to products, services, or interests. Esoteric implies competence with the subject.
Unheralded adjective Not previously announced, expected, or acclaimed From 'more examples': True, he is still no giant, but we have now been introduced to yet another previously unheralded ordinary man. - ODO
A herald is a type of announcer. The idea here is that the person you're describing isn't widely known because they are not announced to the world even though they may have a sizable following or are remarkable in some other way.
I suggest subculture
group that has beliefs and behaviors that are different from the main groups within a culture or society
You might try offbeat:
different from the ordinary, usual, or expected
(I recall that Quantum Leap was always described as offbeat, but it seemed quite popular to me...)
- belonging to the specialized terminology of a group.
- jargon is close in meaning to argot but perhaps is less appealing in adjectival form.