Despite appearing in David Pringle's canon-building Science-fiction: The 100 Best Novels 1949-1984 John Varley's debut novel The Ophiuchi Hotline (1977) doesn't get the same kind of reverence that other books on that list from that era still do.
That's because it's neither a fan favourite (hey there Dune) nor respectable literary SF (Oi! Ballard!). It is what it is - a good first book chock full of pulp tropes, which also manages to anticipate a lot of the genre's pre-occupations and tropes in the coming decades.
The titular Hotline is an interstellar comms channel broadcasting ideas, technologies and scientific breakthroughs at the solar system for reasons unknown, from the direction of (nearby, in galactic terms) Ophiuchi 70.
Humanity has used these discoveries to make the rest of the solar system habitable, Earth having been returned to the Stone Age by (deep breath) 4th dimensional beings intent of preserving the planet for superior intelligences - that's whales and dolphins to you and me.* Where the remnants of human civilisation cannot bend the planets and moon to their will, they adapt themselves to them instead, using the genetic advances and cloning process shared by the Hotline.
Yet now the Hotline is broadcasting a bill for services rendered - what is our protagonist Lila, genetic engineer on the lam, to do about it?
Enough about the plot, which in the fine tradition of first novels throws enough material at the wall for five hoping that it willl stick, and let's talk about what makes Hotline still interesting: the window dressing.
Varley gives us a novel set (mostly) within the constraints of the solar system, taking us back in one way to the planetary romances of the interwar generation, in another imagining what societal and biologial changes humanity would go through to make such colonisation possible.
Or to put it another way, Hotline is a novel about 'software', where the engineering in play is mainly genetic and cultural, rather than the hardware 'n' hard science of science-fiction cliche.
Chronologically speaking, it's also the first novel about being or becoming posthuman in a modern sense I can think of, mapping out a course that writers like Bruce Sterling (Schismatrix), Charles Stross (Accelerando) and of course Iain Banks would follow at various points in the coming decades. All authors also partial to an assertive woman-of-action protagonist like Lila.
Varley also embeds the idea that alien intelligence would be - if not ineffable or incomprehensible - then at least able to think round humanity in circles. Again, this is common currency in SF nowadays, bringing back an element of wild, Lovecraftian horror to the tamed myth of the little green man.
Of course, as any pre-'76 Cleveland punk will tell you, you don't always get prizes for being ahead of your time. And while Hotline was well regarded in its day, the kind of cultural change it envisages (nudity! free love!) is very, well, 1970's.
And the sheer daft effervescence of the plot - endearing as it is - gives it one clear foot in the old-school past in the way that, well, the above authors don't.
So it may well be that Hotline's legacy is to have been a transitional work in SF - pointing a way forward along with others to a new and broader understanding of space-going fiction. Maybe less tumultuous than the disruption of the late 60's, but radical enough that the genre is still working out some of the implications today.
*Hotline predates The Hitch-Hikers' Guide To the Galaxy and its take on cetacean intelligence by a year or so. As whales were a hot topic in the 70's I'm inclined to regard this as an example of convergent literary evolution.