My choices range from "you are all part of the same family" and "you all had the same childhood friend who died" to "you are all on the same train as it's being attacked by aliens, and you need to act fast". I reveal the reason for characters to be there during recruitment, and then allow my players to incorporate that reason into their story however they need.
A thing I avoid, though, is placing characters in captivity at the start. Or ever. Starting in captivity feels like telling a player: "You were dumb enough to let your character get captured in a cutscene." For the same reason I avoid starting with "you all died and were resurrected by GMPC" and "you took a loan from a mobster and now you owe him". Some of these might work in a movie or a book, but that is because the entire story is written by the same author. GMs, however, aren't the authors of PC's.
cowleyc says:
As a PC: What are some good experiences you've had in the formation of a party? What are some techniques you've seen that you liked? Do you mind hand-waving the meeting and getting right to the action?
My best experiences usually include either solo-prologues, in which I eventually get to roleplay how my character meets another character; or
in media res starts, where everyone gets to shine immediately and then that becomes the foundation for future character interactions ("Hey, thanks for that heal back then. What magic was that?").
I also think that under no circumstances should GM describe PC's actions or decisions at any point of the game, including the introduction. Even if the game begins in the middle of things, the opening scene should be ambiguous enough to let players keep their full agency. "You killed them all" in
Qralloq's example is one such problematic description. "Around you there are six dead men. Killed." would be much better.
WhtKnt says:
As a GM, I enjoy dropping them
in media res, getting right into the action. Nothing gets a player's interest better than the words, "Roll for initiative." I start with the characters in a lightweight battle, nothing they can't handle fairly easily, and refuse to provide any details until the battle is complete. Then I brief them on what has brought them to this point.
I agree with
vicky_molokh on this one. While I like
in media res starts, this would be an example of how not to do it. And I suspect I'll state an unpopular opinion, but "roll for initiative" phrase actually makes me yawn. So when you say "Nothing gets a player's interest better…" I'd like to point out that not all players are the same, and starts like that can push some people away immediately. But it's much worse if players didn't know what sort of game they were getting into and then have to deal with an unexpected, unexplained, and unappealing opening scene that was based on assumptions of what they want.