All this happened, more or less is perfect because it sets out everything and brings you in, in so few words.
Vonnegut doesn’t mess about, does he. Straight to the point.
Another Vonnegut gem of an opening line:
“A sum of money is a leading character in this tale about people, just as a sum of honey might properly be a leading character in a tale about bees.”
-God Bless You, Mr Rosewater
See also:
“This is the saddest story I have ever heard.”
- The Good Soldier, Ford Maddox Ford
Jane Austen’s “It is a truth universally acknowledged…” is a different kind of opener. It’s brilliant because a) it’s funny, and b) it tells you what the whole story is going to be right from the off.
But I prefer openings like that passage from The Long Goodbye mentioned earlier - not a pithy one-liner but packs a whole lot of background into one short scene, none of it obviously expository.
Another favourite:
“On my naming day when I come 12 I gone front spear and kilt a wyld boar he parbly ben the las wyld pig on the Bundel Downs any how there hadnt ben none for a long time befor him nor I aint looking to see none agen.”
- Riddley Walker, Russell Hoban
So much to unpack in just those few lines.
Certainly for movies, The Matrix, more so if you went in with no clue as to what it was about.
Oh yes - first time I saw it, I knew practically nothing about it and the opening scene left me breathless.