I know this topic has been covered before, by other capable bloggers, but I'll go ahead and throw in my two pence, for what it's worth.
Here's, my 8 step process to writing a gamebook:
1) Core Idea
First, come up with your idea. For me, this is usually a setting, or a character, or a certain decision I'd like to throw at the player, or some combination of the above. It usually starts small, but it can grow from there.
2) Flesh out the Story
For me, this step involves a lot of creative planning and random brainstorming. Sometimes I'll do free-writes on the computer. Other times I'll scribble all over whatever piece of paper is handiest. You want to answer the following questions:
- Who are the main characters?
- Why does the reader care? What challenges do these character face?
- What important choices will the characters face, that you can torture the reader with?
- What kind of setting will provide the best backdrop for the story? Ideally it should be both colorful and thematically appropriate. Sometimes, especially in science fiction, the choices a character must make are only possible given the inherent laws of a certain setting.
- How many major diverging branches to your story do you want to tackle? Strike a balance between replayability and how much you're willing to ask of yourself. Take your own limits seriously; it's easy to say, "I'll do it all!" but gamebooks will bloat rapidly if you let them, and every human, even you, has a limit. Make sure big branches in the story are based on important decisions.
- What will the ending be? This is often a chance to pop the "Big Question" of your gamebook, or to throw a Boss Battle at the player, or both.
- Where do you want to begin? Beginnings should introduce the most important characters, and set the tone for the rest of the gamebook.
3) Notes! Notes! Notes!
In step two, we did some heavy brainstorming and started putting it all together and answering the big questions. Now, write it all down. Compile final-ish information about...
- The Setting
- The Hero or Heroes
- The Villain(s)
- Supporting Characters
- Technical information about the world (how magic works, what spaceships are available, and what the differences are between them, how the system of mystic seals that grant shapechanging ability really works, etc.)
- Maps and place names
- Etc. You get the idea. Different stories will have different requirements for notes, with some areas being well-detailed, and others left more vague.
4) Plot the Flow-Chart
This is a critical step, like storyboarding for a comic, or outlining for a novel. You usually don't want to just jump in, because you might write yourself into a corner and find that you don't have a way out of it. I didn't learn to write long-form until I learned to outline. Before that, I would run into a problem I hadn't anticipated, not know what to do next, get frustrated, and the story would go to the back-shelf graveyard.
In this stage you want to get a big white board, or a sheet of graph paper, or some appropriate computer program (I don't have one, but I assume they exist) and draw out the path of your story, including major branches and decision points. You don't need to work out every detail at this point; you can write in chunks, ie. "Explore dungeon #2," and the possible outcomes of those chunks, ie. "If find the jade statuette, go to reward sequence, if lose the statuette, go to the docks scene for fight with villain." Draw the lines connecting all the options. It's a big "if-then" logical flowchart.
This step is the essence of writing the gamebook. It's hard, but if you tackle it as it's own problem, you may find it easier than you think. Once you complete this step, there's no reason why you shouldn't be able to finish your gamebook.
5) Write the puppy.
If the flow-chart is storyboarding, then writing is penning and inking. At this point, you should basically know what needs to happen in each scene, and you have a rough idea of about how many sections you have to allot to each scene. You'll do another mini-flowchart for each scene, either formally or just in your head, and then just sit down and write it out.
At this point, you've done the hard work. This is the fun part. But a warning: Make sure to leave enough ambiguous that you still have room for some creativity in the final writing. I've tried plotting out every single paragraph section before beginning the writing process, and it can be kind of boring to plod through writing all the sections, when you've already decided what happens in each and every single one of them.
Send it to all your friends and beg them to tell you the worst things they can think of about it. Then suck it up and listen to their advice. It's probably good.
At the end of the day, no one can tell you what to do with your story. You have to decide for yourself which advice is worth keeping, and which you can safely ignore. But think very hard every time someone voices a complaint and you don't take steps to make that aspect of it better. If one person has a problem, others may as well, and all it takes is one critical problem to make people hate or, worse, forget your creation, no matter how precious it is to you, or how much brilliance the rest of it has.
You may also be informed of things that you never thought of during this stage. Like, "why didn't the hero just get off the ship after the pirates threatened him?" Sometimes this will have an easy answer. Like, "oh, I forgot to mention the ship had sailed out already by then," or "There are sharks." Other times, you'll need to seriously re-think your plot.
Don't be afraid to hack and chop and make serious changes. Text that's lost when you re-write whole chapters is not wasted. If you'd never written it in the first place, you wouldn't have known how to do it better the second go-round.
7) Randomize and Sort the Numbered Sections
Up until now, almost everything could apply to any writing process. This is one that uniquely belongs to gamebooks. Maybe other people have other ways of doing it, but I number the sections more or less in the order I write them, as I go along. If you do it this way, then when you're done, you need to go back and randomize all the numbers, so that the reader won't be able to see the results of both choices he's facing by simply looking at the next two, consecutive entries.
This is a big chore. Be meticulous. It's important! Otherwise you'll end up sending someone who walks through an inn-door into the dragon's lair on another continent. What I do is make a big chart and map every section number to a new, randomized section number, then carefully go back and change all instances of the original section number to the new number. What I've discovered is that if I append multiple zeros (ie. 0012 instead of 12) to every section number in the first draft, then I can use find-replace much more effectively during this stage.
Unlike other steps, this step is consistently harder and more annoying than you anticipate. No matter how careful you are, there will inevitably be mistakes. Go through it with a fine-toothed comb, and you should get most of them. Hopefully your publisher will be nice enough to let you go back and correct the minor errors that remain, later.
8) Final Editing
This is the final round of editing, and if there is any stage to NOT skip or skimp on, it's this one. Send it to all your friends again, and ask them in your nicest voice to read it one more time to look for any errors at all. You may want to offer cookies.
Alternately (or in addition) it's worth it to hire a professional copy-editor to take a look at it. Nothing says amateur and shoddy craftsmanship like having a text that's full of grammatical and spelling errors, in which the numbered links don't take you to the right place.
At this point, avoid making any major changes to the story flow. You will probably realize it's not perfect. Bite the bullet and accept it's as good as it's going to get. No artistic project is ever done, it's only good enough.
Once you've gotten the text as clean as you can (resisting the urge to make any major changes), then you're done. Congratulations! You've just written a gamebook! I honestly believe most people have stories to tell. Yours is probably good; probably better than you think. Send it out there and see what the world thinks of it!
That of course, gets into marketing, which is a whole other beast. My suggestion: start with some competitions. If you can win, or at least get recognized in some writing competitions, it will be a lot easier to get publishers to take you seriously. The Windhammer Prize for Short Gamebook Fiction is currently open for submissions, and is a great place for amateur gamebook authors to showcase their works!
Good luck, and let me know how it goes! If you ever get stuck and need some advice, or want someone to look over your works, let me know! I will read, or at least look at, anything anyone sends me :)