Openings

Many factors external to the text of a novel alert prospective readers as to whether this work is mainstream or genre fiction before they have even opened the volume but how soon does the text declare itself? 

Lewis 

The Preface to CS Lewis's The Hideous Strength explains that this novel is sub-titled "a fairy-tale" because its opening chapters read like contemporary fiction, giving no warning of the later magicians, devils and angels. Lewis acknowledges that some readers dislike fantasy.

 

Blish

"The stone door slammed. It was Cleaver's trademark: there had never been a door too heavy, complex, or cleverly tracked to prevent him from closing it with a sound like a clap of doom."

-James Blish, A Case Of Conscience IN Blish, After Such Knowledge (London, 1981), pp. 523-730 AT I, p. 531.

Those are the opening two sentences of a novel by James Blish: so far, no indication of genre. However, the third sentence:

 

"And no planet in the universe could possess an air sufficiently thick and curtained with damp to muffle that sound - not even Lithia." (ibid.)

- both completes the opening paragraph and confirms what we probably already knew, that this is sf. 

 

(IIRC, the publisher queried whether the title was appropriately sfnal.) (Another interesting feature of that opening sentence is that BOOK ONE, originally a novella, concludes: "The air lock door slammed." (p. 615) as if to symbolize Cleaver's triumph over his antagonists.)

 

Anderson

Skipping, at least for now, past the unheaded italicized passage preceding Chapter I of Poul Anderson's A Knight Of Ghosts And Shadows, we find:

"Every planet in the story is cold -..."

-Poul Anderson, A Knight Of Ghosts And Shadows IN Anderson, Sir Dominic Flandry: The Last Knight Of Terra (Riverdale, NY, 2012), pp. 339-606 AT I, p. 342.

In this case, we do not need to finish reading that opening sentence. Its opening phrase, indeed its second word, is sufficient - whereas the title alone might have suggested fantasy or medieval romance.

Incidentally, those planets are:

Terra

Diomedes

Talwin

Dennitza

Chereion

- a good mix of the familiar and the new. Only Dennitza is entirely new.

This post refers to CS Lewis's Ransom Trilogy, James Blish's After Such Knowledge Trilogy and Poul Anderson's Technic History. Read or reread all three!

As for the rest of the text of A Knight Of Ghosts And Shadows, that still awaits us.