I don't know how people come up with their stories but I can tell you how I come up with mine. I don't start with scenes or characters or settings or genres. I start with a tone and a theme, because those two things provide the guiding light as I try and uncover everything else.
When applied responsibly, a theme can give a work of fiction its center of gravity, and can make the experience feel meaningful and open to interpretation in a pleasing or thought-provoking way. When applied irresponsibly, a theme can make a work of fiction feel condescending or didactic, like you got tricked into taking a call from a telemarketer.
A theme ought to be omnipresent but subtle. If the audience can identify the theme easily then it's too over-the-top. If there's unanimous consensus about the theme then it's also over-the-top. A theme is like the body language of the work. It should give a strong impression to those paying close attention while operating on a subconscious level in most cases.
A theme is not a moral. It's an open question, not a conclusion. It needs to be an open question because an entire work of fiction needs to be created in its service. In thinking about new stories, I like to think of themes in a journalistic way. My responsibility as the writer is to fully explore a given theme, to provide the audience with a wide breadth of relevant information which can be used to draw various conclusions.
The tone of the work may inform the theme, or vice versa. The combination of the two create the identity of the work, a subject I'll explore in more detail in my upcoming GDC 2012 talk about creating atmosphere in games. (EDIT: The slides for this talk are available here.)
The story I wanted to write for Bastion was intended to explore the theme of overcoming regret. The tone I wanted for it was bittersweet but not sentimental, cautiously optimistic and ultimately hopeful but still melancholy at times, something that felt real rather than sappy but still could be suitable for almost all ages. The characters, events, places, and various little details all came about in support of these ideas. The theme ended up serving as my map. The tone served as the directions from the starting point on that map to the end point. I knew the starting point and end point early on. Plotting the course is what took the longest amount of time, mainly because I didn't write any in-game content before we had playable levels that needed to be written.
I don't like spelling out the theme like this but the game's been out long enough, and besides, it's a broad enough theme to where spelling it out doesn't really matter. The theme in and of itself is too broad to be susceptible to judgment. I think that's the mark of a theme worth exploring.
You'll notice that the theme I chose is simply "overcoming regret", just two words, as opposed to something like "in life we all need to learn how to let go." One is a theme, the other is asinine. Because I'm not Aesop, I will never, so long as I'm blessed with the opportunity to continue to create games, ever inflict my morals on you. I have my kids for that. Besides, if the theme I chose could be reduced to a fortune cookie sentiment then it isn't strong enough to bear the weight of a story worth telling.
The theme of a game's story ought to be the theme of the entire work, or vice versa, however it all comes together. If a game's story has a theme that's not supported by the play experience itself, the game threatens to feel disjointed and leave a sour taste with the player. In Bastion's case, the game was always going to be about building the world around you, an aesthetic idea and a design idea that naturally extended to a theme. The idea of building gave rise to the idea of rebuilding, which gave rise to the idea of overcoming regret and this post-disaster story about a few survivors (and other creatures) dealing with what happened in their own way.
All of the different game systems ideally should support the theme. With this in mind, in Bastion we tried to solve for some problems that can induce a sense of regret in other role-playing games, such as when you get the sinking feeling that you chose poorly when developing your character. In many RPGs, you're asked to make half-blind choices about character class or perks and stats. Halfway through the game you find yourself wishing that you chose differently. This can create incentive to replay the game but it can come from a negative place. In Bastion, we offer the player complete freedom to customize their character all the way through. Our difficulty system, via the Shrine, works in a similar way. We don't make you choose the game's difficulty before you've had a chance to play it and get a feel for it.
There are other smaller examples. When you run out of health and get defeated, you have the opportunity to "carry on", get back up at least one time and keep fighting. It's just a system of extra lives, superficially no different from the convention used by countless old games, but in Bastion I think it takes on a different connotation for some players as they see the protagonist character struggling through one situation after another.
Then, when we present players with the game's climactic, expressive choices, those are the only moments where there's no turning back. I think this is self-evident in the choices themselves, and thankfully we got a lot of good feedback from players saying they gave pause in those situations for quite a while, deciding what to do. I'd like to think that almost everybody who reaches those moments in the game ultimately makes a firm decision, not the wishy-washy I-don't-know kind but the kind that feels satisfying and cathartic even if not exactly good.
So, why would I want to write a story about an unpleasant subject like regret anyway, especially for a game that seems to have the trappings of a hack-and-slash action RPG romp? One reason is because I don't want to waste people's time with meaningless game experiences. Another reason is that this theme is important to me for a bunch of reasons I could only articulate through the story itself. I think regret is a universal feeling experienced by almost everyone from a young age. The depths of that regret vary from one individual to the next in a profound way, but on some level there is a shared experience, even among those who've suffered no real losses, who've had it pretty good overall. Me, I'm the sort of person who's spent (or wasted, depending on how you look at it) a lot of time re-playing various scenes from my life in my head, wondering about alternative outcomes. This is typical but I think I have an acute case of it. Setting aside whether it's healthy or not, I accept that it's a part of me, and it's the reason Bastion's story is what it is.
Thanks for reading, and may things turn out all right for all of us in the new year.