A Fire Upon the Deep, by Vernor Vinge

If you have a taste for epic sci-fi with imaginative world-building, intricate plotting, and varied characters and settings, Vernor Vinge's A Fire Upon the Deep may strike your fancy.  Since it won the 1993 Hugo Award for Best Novel, sci-fi lovers have lauded it.  Reading it now, 27 years after its publication, I can attest that it has stood well the test of time.

This is the first novel in Vinge's "Zones of Thought" series.  This part of his storytelling is the hardest for me to wrap my mind around.  In his world, there are transcendent beings in different zones of the Milky Way.  As you travel from one zone to another, their reach is limited, laws of physics change, and a ship's capabilities may be compromised.  The Zones are surely much clearer in Vinge's mind than in my reading.

On the other hand, the core of the story is much simpler: two kids crash on an alien planet whose technology is similar to medieval times on Earth, and whose dominant species is a race of dog-like beings with hive minds.  Light years away, a transcendent being has begun destroying entire planets.  A couple of humans believe the secret to stopping it is on the ship the kids were on, so they begin a months-long journey to find them.

The key to the story is that the choices and acts of insignificant people (of many species) have a far-reaching, consequential impact on the very structure of the galaxy and the fate of billions of its inhabitants.  A small boy's relationship with the dog-like beings he now lives among, the human researcher's relationship with a man who first lived thousands of years ago, a research station's inadvertent release of a powerful entity, the tribal conflicts of a bunch of pre-modern packs of sentient dogs, it all works together to shape the destiny of the galaxy.

A Fire Upon the Deep may not satisfy some readers.  It's a mash-up of sci-fi and fantasy, with the extensive history of space-faring species on one hand, and the packs of dogs living in medieval castles and using bows and arrows on the other.  I wouldn't call it hard science fiction, but it sure is fun, entertaining story telling.