So You Want To/Make a Visual Novel

Okay, so you want to make a Visual Novel. Great! You are about to add a new work into the newest medium of art! Oh, and before you ask, Dating Sim =/= Visual Novel. Romance-focused Visual Novels and Dating Sims do have similar plots, but the former is more akin to a novel while the latter is more akin to a RPG. While those works have their own section at So You Want To/Write a Dating Sim, this section will cover visual novels in general regardless of the genre. Yes, there are Visual Novels of every genre. Regardless of the genre you plan to make the Visual Novel in, this guide's goal is to assist you. So here we go!

The Engine
The first place to start is the engine for the Visual Novel itself. While it's certainly possible to handle all the technical stuff yourself from scratch, there is a wonderful open source Visual Novel engine known as Ren'py. It's easily accessible to someone with almost no coding experience, and comes with numerous tutorials to get you started. But selecting an engine is just the foundation, and the process of creating a Visual Novel is still the process of creating a story.

A Very Unusual Medium
So visual novels are just electronic books with fancy anime pictures and music, right? Wrong! While many can undeniably be described as that, others like Muv Luv Alternative have Visual Effects of Awesome so great they have action scenes akin to movies. Alternatively, there are those that are like interactive manga such as Quartett. Text and dialogue are undeniably the most important aspects of a Visual Novel, but do not neglect the visual or even audio aspects of them. Presentation is important, after all.

The Visual Aspects of a Visual Novel

 * Backgrounds: While many people don't care if you just take real pictures and use a watercolor filter to save money on backgrounds since it is a common tactic of many amateur visual novels, they are still important. It's a lot of work, but hand drawn sprites just look better on hand drawn backgrounds. Furthermore, with self-created backgrounds, you can create your own unique atmosphere. Just look at Sekien no Inganock with its fancy and artsy backgrounds which complement the text and the characters.
 * Character Sprites: Good luck. Each major character in your theoretical VN will need at least half a dozen sprites. While it's recommended for beginners of any kind of story to avoid using Loads and Loads of Characters, this is especially important for visual novel makers. Even minor characters will need multiple sprites since sprites are the best way to convey a character's emotions.
 * Too bad, you can't attract players using screenshots from visual novel with poorly drawn character sprites. It's what turns off people from many amateur Visual Novels, yet not everyone can draw smoking hot characters. How to get around this? You have two choices. 1. Spend years mastering the art of illustration. Perhaps attend art school. Hone your craft until you can fully realize your character just as you imagine them. 2. Hire an artist for your project (or ask from very generous friend with good drawing skill)... Still not sound like a valid choice? Well, When They Cry series can get away with it because the facial expressions of the characters in the Umineko series are considered awesome. (Faces are what people focus on the most.)
 * Computer Graphics or CGs for short: These are still images made to appear when certain scenes occur. These images are best used to convey events that cannot be shown accurately simply by moving the character sprites such as a First Kiss, a Dying Moment of Awesome, a Transformation Sequence, baking cookies, and of course, sex, or make the importance of a scene obvious such as a Moment of Awesome or a Plot Twist.
 * Special note: DO NOT MESS THESE UP! It's far better to have no CGs than to have bad CGs. No one likes to be forced to look at a badly drawn or badly colored picture that takes up the whole screen. Even minor mistakes are very noticeable and can ruin the immersion a player has. A notable example of unpolished CGs ruining a game is Don't take it personally, babe, it just ain't your story. The character sprites are fine, but the minor mistakes in some of the CGs can ruin the moment.
 * Special Effects: Sure, they may not seem important, but a couple of well-placed special effects can go a long way. Visual effects books cannot use can be used by visual novels. A flash here or falling snow there, can easily enhance the amount of emotion any given scene can enhance. Even something as simple as moving a sprite left or right or the way the text is shown on the screen is important! Quartett is a great example of sublime visual presentation of the story text itself and use of visual effects to evoke emotion, and Umineko no Naku Koro ni is a great example of using special effects to Paint The Fourth Wall and to use them as a plot point.
 * Ways of presenting the text: There are multiple ways, but the two major ones are ADV (short for Adventure Style Game) or NVL (short for Novel Style Game). There are advantages and disadvantages to both major styles.
 * ADV: The more common style. Basically speaking, all the text of the visual novel is put into a dialog box in the bottom of the screen. While this forces the writer to focus on a script-based format with minimal space to describe the setting or character actions, the background images or CGs can do that for you since a picture is worth a thousand words. This type of style leads to a visual novel with a large emphasis on the visual aspects of the Visual Novel, so it is a terrible style to use if you suck at drawing and are more used to writing in pure prose. A common pitfall is for an amateur prose writer to attempt this style simply because it is the most common one (and the default style of Ren'Py).
 * NVL: The best format if you want less of a focus on the visual aspects and more on the actual writing since text covers the whole background and forces the reader to actually read rather than look at the background images. Part of the reason why Umineko no Naku Koro ni can get away with it's lame art is because it uses this particular style. It is also the best style to use if you tend to be very descriptive in your writing or like Stream of Consciousness style internal monologues like Nasu. Some visual novels that normally use the ADV style like Sharin no Kuni or even Katawa Shoujo have a few brief NVL scenes to highlight important moments and to describe them in detail.
 * Others: An interactive comic book style like Quartett, a minimalistic letter box style like Narcissu, a Diegetic Interface like Digital: A Love Story, or even one with vertically oriented text.

The Audio Aspects of a Visual Novel

 * Background Music: The major reason why a visual novel can get away with a lower quality of wordsmithing than traditional novels is because of this. Other than Grammar Nazis, no cares if a phrase is a tiny bit awkward if Awesome Music is playing in the background. The background music has to complement and enhance the text it is behind. Describing a soothing Slice of Life scene? Then use calming music! An action scene? Heavy Metal, of course! A Plot Twist goes great with Ominous Latin Chanting, and so on. You could also try using Soundtrack Dissonance to complement Black Comedy or Mundane Made Awesome. Music is important, dammit! The When They Cry series is so good at the music (and so bad at the art) that they are called Sound Novels instead.
 * Sound Effects: Like in any audio/visual media, a well placed sound effect can have a great impact. They are especially important in action based visual novels like Demonbane or Fate/stay night.
 * Voice Acting: Ha Ha Ha No. Unless you are a professional who can hire professional voice actors or miraculously have good amateur voice actors despite Sturgeon's Law, then please don't add voices. Good voice acting can enhance a Visual Novel, but anything less would ruin it. Let the reader imagine the voices like they would in a traditional novel if you're an amateur.

Video Game Aspect of a Visual Novel

 * Do you want to add game mechanics to your VN? If not, skip to the major bullet point. If, for whatever reason, you do, then read on.
 * Relevance: Make the gameplay reflect the Genre of the Visual Novel as a whole. For example, if the Visual Novel is in the horror genre, then give it some gameplay that involves running away from Eldritch Abominations such as in Shikkoku no Sharnoth. If it's a war story, then there better be Strategy RPG elements like in Eien no Aselia. If you want to make a mystery genre VN, Adventure Game elements would go well with it like in the Ace Attorney series. If it's a Porn Without Plot game and you feel like adding gameplay then... You get the idea.
 * Rule of Fun: If you're going to have gameplay, then it better be fun. No one cares how symbolic the Mini Game is if it's not fun.
 * Forced Reading: Yes, you can hijack the player's control of the reading speed and force him to read at your own pace such as in Deardrops or in certain Moment of Awesome concert scenes or in certain Muv Luv Alternative fight scenes. It gives you, the maker, more control over how you want the player to experience a certain scene. Just don't use them too much because it can break the immersion of some players.

Plot Structure
In other words, how your story is broken up into the various routes you may have. However, the first question that must be asked is "Do you even want your Visual Novel to have multiple routes?"
 * No: You could always make a Kinetic Novel or Linear Visual Novel. There's nothing wrong with focusing all of your effort onto one plotline and making it good. Muv Luv Alternative is one of the most highly rated visual novels despite being a Linear Visual Novel.
 * Yes: How will the routes tie together? Will you use a Multiple Route Mystery like Remember 11? Have them all lead up to a climatic final route with the True Ending like in Little Busters!? Share the same fundamental Aesop like in Katawa Shoujo? Of course, you could make them have no relation to each other at all like in Kira Kira, but they all better be individually good. Just please don't tack on the routes just for the sake of making all the girls date-able like in G Senjou no Maou.
 * Common Route: It goes without saying that you'll need one to contain the choices that will decide which of the multiple routes a player will go on, but what type of length do you want to make it?
 * Long: The upside is that you will have plenty of time to develop all of the characters at once through their interactions and establish the setting. The downside is that a few of the individual character routes may suffer because you don't get enough time to focus and develop on a single character and make up good plot related to that person. Hoshizora no Memoria in particular suffers from this problem.
 * Short: The upside is that you have plenty of time to make up unique conflicts for each route by giving yourself enough time to add build-up within the diverging routes themselves and only leaving small tiny hints within the common route itself. The downside is that it gives you less time for World Building or you have to copy/paste text between the routes. Tsukihime has this problem to some degree even though it has a recommended route playing order. Fate/stay night removes the problem by having a forced playing order, but the first route's quality is sacrificed for the need to establish the setting.
 * Diverging Routes: A common way to split them is by centering the individual plotlines around a specific Romantic Interest. That being said, don't be afraid to have a Heterosexual Life Partner route like Clannad.
 * Choices: You need some, but not too much. Furthermore, make them intuitive or at least solvable with some thinking. Kara no Shoujo is known for Guide Dang It for having too many and too unintuitive choices.
 * Bad Ends: You could just add a short event where the protagonist dies or falls into despair before showing a Game Over screen, but you know that you're better than that. Why don't you try punishing the player by forcing him to read a emotional Tear Jerker or some scarring Nightmare Fuel. School Days has such potent bad endings that it is generally believed that while School Days is decent on its own, the bad endings are what make the game a classic.
 * Final Route : It better be good. If you decided to have one of these, that means you stored Up to Eleven amounts of pure build up. Mess this up, and you mess up the whole VN. In other words, don't attempt this unless you have strong idea of what you're doing.

Writing Style
You know the writing techniques for prose and poetry some people use like Gratuitous Iambic Pentameter, Repetition, Alliteration, Allegories, Symbolism, and so on? Use them! Just because Visual Novel readers are more lenient on wordsmithing because of Background Music doesn't mean that you shouldn't try to have good wordsmithing. Incidentally, the Japanese version of Sekien no Inganock uses very poetic writing, but its fan translator had to use prose for the Fan Translation.

Characters
Especially in the ADV style where you are forced to rely mostly on dialogue to tell your story, characters are the most important component of a Visual Novel. Background Music can cover up any weakness the prose has in creating the atmosphere. Plot events can be shown with CGs rather than told to follow the philosophy of Show, Don't Tell. Character personalities have no such fail safes even in a visual novel. An awesome Leitmotif or cool looking character sprites can help, but a weak character leads to weak dialogue which leads to weak storytelling. Weak story telling can easily ruin a plot.


 * The Protagonist: Lets break down to various archetypes, from sliding scale of moral. Pick one that fit your story best.
 * Nice Guy: Your visual novel will be most likely in first person point of view, and thus Nice Guy archetype is the sensible choice, right? Too bad -- the fact that nice guys are very common as protagonists means it's hard to make the character stand out, plus Good Is Boring to many. You do want to avoid Designated Protagonist Syndrome, don't you? Still, if you plan to use a Featureless Protagonist, this plain good guy offer the best template.
 * Troubled but Cute: Similar to the nice guy, but with flaws, they may have some hidden things about them that are unsavory or make them somewhat unlikable.
 * Jerk with a Heart of Gold: Somewhat unlikable protagonist.
 * Jerkass: Highly unlikable, although what they don't go around and commit crime For the Evulz.
 * Complete Monster: An outright Villain Protagonist. Despite being polar opposite to the Nice Guy, it's actually much harder to write about a Complete Monster, as you're writing about a Designated Hero anyway.
 * Blue and Orange Morality: As malevolent as the Complete Monster, but they aren't much evil as being of an alien mind.
 * Other Characters: If you have multiple routes and they are centered around specific characters, be sure those characters are interesting. Since individual routes have less characters, if the character the route is centered around is uninteresting, then there's a significant chance the player may utter the Eight Deadly Words. Even if you are doing a Linear Visual Novel, it should have interesting secondary characters like any other story.

Warnings

 * Don't bite off more than you can chew. Katawa Shoujo (a Medium length Visual Novel) took five years for a reason. A Visual Novel requires an organized team of artists, musicians, programmers, writers, and editors. Don't forget about the potential infighting an amateur group may have when a project is too big. Start small.
 * Substance over Style: Nothing can save a Visual Novel if the story it tells is So Bad Its Horrible. Bad art can be counteracted with good music, bad music can just be muted or be counteracted by good art, but good visuals and audio can't save a bad story.
 * List of Cliches that are extremely common in visual novels: Groundhog Day Loop, Ill Girl, Rape as Drama
 * Vaporware: Creating Freeware Games of any kind, including visual novels, is a long and often frustrating process. If you can not (or choose not to) charge money for your final game, then it can be difficult to keep writing and coding until it's finished. Some people who aspire to create freeware visual novels give up, leaving nothing more than a few paragraphs of description and perhaps some concept art. Other people finish a demo, and the final version ends up in Development Hell. If a group decides to collaborate on a freeware VN, then it may be more likely to remain unfinished. Either way, if months go by with no substantial news, then the VN has likely become vaporware.