You know me, I can't resist smashing that "Random Item" button.
I thought so. Well, a Dialogue Tree is a common feature of Role-Playing Games and Adventure Games, where interactions with certain NPCs are done by selecting a possible response from a list of two to five choices. As you might imagine, this can lead to frustration as the player tries to figure out the correct sequence of responses to get what he or she wants out of the NPC.
Sounds annoying. So why even use them, then?
But they can't be all bad if they're so common, right?
I think I missed something, can you start your entire speech over verbatim?
You put the "start over" response at the top just to screw over the players rushing to end this conversation, didn't you?
Okay then. And remember, nothing's more annoying than the illusion of choice. And on that note, how would you like to do a long and tedious Fetch Quest? See, I need Twenty Bear Asses for no adequately-explained reason, and I have a hunch that the Broken Bridge out of town won't be fixed until I get them. Will you help me?
Link from The Legend of Zelda is a strange case. Unlike everyone else in the series, he never gets a regular dialogue box, making him a Heroic Mime. He does, however, frequently get dialogue trees, ranging from a simple yes/no to humorous retorts.
Used in most adventure games. Sam & Max Hit the Road was unusual in that it replaced questions or topics with graphical icons representing things you could ask about.
The graphical icons were also used in Discworld point-and-click games.
The Broken Sword games also use icons instead of real text, and you can even talk about/use your inventory items in conversations.
The Dig used icons as well, but made a joke out of repetitive dialogue. After learning about the in-game bridges made of light, Boston Low (the PC) can call up another crew member and speculate at EXTREME length about other things you could make out of light. Light house, light salad dressing, light beer... The first few amuse your NPC crewmember, but she gets more and more annoyed as you go on.
The X-Files Game allowed you to select what kind of emotional response your character would give to certain lines. In an interesting take, certain events would change depending on how you decided to respond: for example, picking mostly "paranoid" answers would cause a dead body to suddenly twitch at you in the morgue.
Hotel Dusk: Room 215 mostly has this when talking to other characters. Sometimes you show/give them items. Sometimes Kyle just speaks and you cannot do anything. It also adds the ability to 'file away' important phrases and interest points, which you can question the person on in the next break in conversation, or question other people on later. It also allows you to interrupt people when they say something interesting and interrogate them further, or just let them keep talking.
Its sequel, Last Window, had one puzzle near the end based around a dialogue tree. You had to select the conversation options in a very specific order to prove Kyle knew what was going on. One mistake lead to a Game Over.
One of the selling points of Grim Fandango is that it has "over 7,000 lines of revealing dialogue".
Discworld Noir has these, which is unsurprising for an adventure game. It adds that you can bring up any item in your inventory as a conversation prompt, along with notes you've made about topics you've encountered.
Fahrenheit has perhaps a unique manner of conducting dialogues in real time! Every time you get only about 2 seconds to choose a line (neatly presented in forms of brief notions, like "tell truth" or "turn into a joke".) Fail to choose in time and the character will blurt out one of them at random.
Spiritual successor Heavy Rain allows you to do the same. It even gives you Inner Monologue Trees when it comes to listening to your characters' thoughts!
A Tale Of Two Kingdoms has standard dialogue trees, but with the added option to ask people "could you do something for me." This lets you ask the NPC you're speaking with to look at or touch anything in the room, which gives different results than if you do it yourself.
One of the earliest games to attempt this was Windham Classics' Alice in Wonderland game. When conversing with a character, you had options like "Coax," "Tease," "Scold," and "What are you doing?" Picking the right answers yielded clues or items to advance. Angering one of the Wonderland residents would cause them to vanish for a few in-game hours. This being Wonderland, polite behavior wasn't always the best course of action.
Completely averted in the Starship Titanic game - it really can read full, typed out sentences and has a huge number of recorded responses.
The Sakura Taisen series has a variation. You usually have a time limit to choose from the dialogue choices given to you; if you didn't pick anything before time ran out, the character you were talking to would treat it as the player character deliberately remaining silent. (This wasn't necessarily a bad thing.) Sometimes, additional options would appear halfway through the countdown.
The Love Hina GBA game does pretty much the same thing.
Somehow manages to turn up in a climactic level of World of Goo, despite it being, roughly, a puzzle game. Subsequently it gets a big Lampshade Hanging (see the quotes page).
Gunpoint lets you choose between being serious and professional or being a Deadpan Snarker pretty much every time you get to talk. It has no real bearing on anything gameplay- or storyline-wise, but making conversations go in a typical internet fashion is kinda nice.
At one point you get an option prefaced with "(Lie)". If you pick it, the character you are speaking to will mention how you put (Lie) in front of all your lies.
Once you've won a cup in F-Zero GX, your racer is taken into an interview room with F-Zero TV host Mr. Zero, where you choose what question he asks. The available questions change depending on your difficulty.
Real Time Strategy
An interesting version occurs in Castles (and would've been a subversion, if the game hadn't been as old as the trope itself!). While building your massive castles, you are occasionally interrupted by a scene of one of your subjects (be it a knight, bishop, peasant, etc.) coming to you with news, threats or advice. The scene consists of some narration and the text spoken by your audience, after which you get to choose from one of three optional responses. The trick is that after your respond, the game goes back to the castle-building mode as though nothing happened. You are then left to pretty much obsess over what implications your decision may have. About 10-15 minutes later, another cutscene/dialogue will trigger, possibly continuing the same plotline from before taking your previous decision into account, or it may be a completely different person starting a new dialogue tree! Some of these "side-events" can continue over a few "years" of game-time, and some can even be circular: going back to square every few cutscenes until you can figure out a way to resolve the situation for good. Of course, some of the choices in certain dialogues will lead to instant battles, and many of these are the most difficult battles you'll face in the game. At other times, a dialogue option can cause half your laborers to leave the building site, or other such dreaded scenarios.
Role Playing Game
Planescape: Torment is built on this, it's used for virtually any interaction more complicated than opening a door or picking up an item, and when used in conversation the trees get obscenely long and elaborate, to the point that you spend far more time in them than actually exploring and/or fighting. Often you even have two identical dialog options, only one of them is you telling the truth and the other is a lie.
Cosmic Solder from 1985 may possibly be the Ur Example in role-playing games.
Megami Tensei from 1987 featured a similar dialogue tree conversation system.
Final Fantasy II (the original, not IV) made use of this, something that was pretty revolutionary for its time, considering this was an 8-bit NES game from 1988. As you played, you would pick up special words used as branches that you could then ask other people about in various conversations. The tree only appeared when talking to specific people though (otherwise, they'd Welcome to Corneria you), and they were only programmed to respond to certain branches at certain times. This made it odd when you tried to talk to Princess Hilda near the endgame with a good 20 branches to choose from, and any besides 1 or 2 still currently relevant choices resulted in her just flinging a "?" at you.
Final Fantasy VI had a scene in which your characters would have a dinner party with Emperor Gestahl. During the dinner, you're called upon to respond to his prompts, such as who to toast at the start of dinner or what to do about the recently imprisoned Kefka. Depending on what you say, and how many soldiers you spoke to before dinner, you'd be rewarded with diplomatic gestures, such as imperial troops being withdrawn or gifts from the Emperor himself.
X-Men Legends II deserves special mention because its Dialogue Trees are a bit more complex: you can get different dialogue from a character depending on whether you encounter him/her as an X-Man, a Brotherhood member, or the one character he/she has special dialogue with.
Mass Effect handles this in such a way that you can choose which option you want your character to say, before the current speaker has finished their line. It certainly helps to keep the flow of the conversation, and prevents most instances of Paused Interrupt. The game also put its own spin on the trope by having you choose only the general tone of Shepard's response, rather than the exact words.
There's even one instance in the climax where you can convince the bad guy to commit suicide simply by using your wily, idealistic charms or your bed-wettingly preposterone coated manliness. Actually two instances, but the second is much harder to accomplish, and requires consistent dialogue choices through the entire third game.
KotOR 2 manages to turn the Dialogue Tree into a Dialogue Weapon twice; early on in the game you have a battle of ideals with Atris, and then much later you're required to use words to erode Darth Sion's will in between bouts of lightsaber combat, effectively talking him into suicide.
Their game Star Wars: The Old Republic will be the firstsecondMMO to feature fully-voiced dialogue trees.
Sonic Chronicles: The Dark Brotherhood uses icons to represent the attitude with which you respond. You usually get a couple of on-topic or topic-introduction options, and a snark or two.
Dragon Age had a similar conversation mechanic to KOTOR where skills and your gender/origin play a part in dialogue. Dragon Age II changes to a Mass Effect dialogue wheel that uses symbols to show attitudes as well, ex. snarky, tough, diplomatic, etc, the choices you choose gradually affect the player character's personality, e.g. lots of snarky responses and Hawke will come out with more funny lines and is better at lying.
Done in a hidden way in Ultima IV. The player could type in ANYTHING they wanted to, to any NPC - as long as it was one word. The only three words that all NPCs were guaranteed to respond to were "Name" "Job" and "Health". Occasionally a NPC in their dialog would let slip a subject that you could then bring up to another NPC - which would reveal that subject him once you asked. This system faded as technology advanced, and by Ultima VII it was a more conventional dialog tree.
Ultima VII goes so far as to lampshade the U4 dialog options. Talking to the troupe of the Britannia Theatre Company in Britain gives you an opportunity to be an understudy for the role of, all things, The Avatar in their upcoming production. The only lines you're given are "Name", "Job" and "Health" and to add insult to injury, you get told you're not convincing enough for the role.
Done the same way in the very similar Exile series. Then, in the original Nethergate, it was made something like a webpage, with certain words you could ask about highlighted. In order to ask about something, you click on a word. The remakes (Avernum series and Nethergate: Resurrection) use a conventional dialogue tree, though.
Also done similarly in Wizardry 8, in that you could ask about any noun or noun phrase and the AI would fill in the question it thought was appropriate around said noun.
The Elder Scrolls II: Daggerfall has a dialogue tree method that uses keywords and divides them into topics and regions of interest. Most information you will learn from these involve updating your town map with store names. Actual quest-based information is handled via a "shut up, I talk, you listen" approach.
In The Elder Scrolls III: Morrowind, you can choose what to talk about with NPCs in a dialogue tree, including "Lore", "Background", and "Race". NPC responses on one topic can contain the names of topics new to the player, allowing the player to select those new topics in dialogue with any NPC having a response to that topic. Certain classes (and individuals) have more responses available: priests will talk about the gods, and savants will talk about pretty much everything in the game, leading to their Fan Nickname of "Walking Encyclopedias". Additionally, some topics are region-based, and will appear in a given NPC's dialogue tree because they had spawned in that region of the game world.
The Elder Scrolls IV: Oblivion's version is limited in comparison. Every character has at least a "Rumors" topic, and city dwellers can talk about their city. Guards will respond to queries about notorious thief Gray Fox and guard captain Heironymous Lex. Some topics are scripted to do things when chosen—for instance, beggars have the "Have a coin, beggar" option, which actually makes your character give them 1 gold.
The Elder Scrolls V: Skyrim has a more traditional dialogue system, where you actually choose what your character says instead of just choosing a topic to talk about.
Used in the Fallout series, with some variation. Most dialogue uses a tree, but you also have the option to type in a keyword, which they will treat as a request for information about the topic, but most characters have few or no options. Later installments stripped out the keyword option.
Fallout is a masterwork of interlocking player character skills (and stats, advantages, and even equipment or clothing) with hidden twists and turns in the dialog trees. The most famous one, however, is low intelligence. A character with a sufficiently low intelligence is too stupid to actually possess a working knowledge of language. The game still possesses dialog trees, it just that they tend to all consist of options like: "Hunh," "Ugh," and "Mom?", with various characters in the game reacting to this utter idiot accordingly. Amazingly, the game is still playable, possessing a whole alternate dialog for the entire game, based around your character possessing the mental acumen of a somewhat clever dog. There are even quest resolutions that only exist with an abysmally low intelligence character.
There is an interesting bug with the character Dane in the cathedral. The parser only prints the last few sentences of his dialogue before topic choices, rendering his conversation even more raving than displayed. His full dialogue is here.
Fallout 2 had a simpleminded character in one of the main towns. If your PC is also simpleminded, you two can have an in-depth conversation, in which the subtitles are subtitled.
Fallout 3 continues the tradition with conversation options for stats, skills, karma and even perk related dialogue. It also probably holds the record number of swearwords you can select in any game.
Fallout: New Vegas adds special dialogue choices for taking a Gay Option, which can even interact with the aforementioned low-intelligence options ("You too tense. It wrinkle your nice face."). There's also a Terrifying Presence perk that lets you interrupt a hostile dialogue with a Badass Boast that not only initiates combat, but sends your opponent running.
The Geneforge series makes use of dialogue trees as well. What you say can have an impact on your reputation (News Travels Fast). Putting points into the Leadership skill gives you more conversation options, making you better able to persuade people.
Albion has universal standard options (eg. you can ask most people what their profession is), a key word system (mostly used for finding about the local culture, but sometimes to advance the plot), and only occasionally actual lines you can choose - and even more rarely more than one that are genuine alternatives. Aside from the smoothness of finding out about local gossip and cultures by asking just about anyone without having to have dialogue options to do that with, this doesn't help avoid any of the problems.
In the first Kingdom Hearts you are asked three questions at the very beginning. How you answer them will determine how hard or easy the game is. In both games there is a similar situation where you must choose various weapons and skills to determine how you will level up and what sort of combat you want to focus on.
Devil Survivor has a number of these for every conversation, and while some won't matter or will just make you choose the other choice later, some have huge effects on story events. Speaking of story events, you choose which ones you do. So there's really a ton of possible ways to go through the game, regardless of there only being 5 (or 6, depending on who you ask) endings.
Rise Of The Argonauts uses a dialogue wheel similar to Mass Effect with the key difference of appealing to the natures of Jason's four patron gods (Ares, Apollo, Athena, and Hermes) instead of a Good/Bad mechanic. For example, Ares choices are naturally aggressive and Hermes' are compassionate.
Okage uses them, but with Ari's sheer lack of presence meaning your choice of response usually has no immediate effect.
Tales of Xillia 2 has much more of this then the previous games in the series, for the sake of putting the player into Ludger's shoes.
Animal Crossing uses this at the very beginning, when you talk with Rover. This will determine your face (which you can't change). In Wild World and City Folk, this also can determine your hairstyle at Harriet's salon. Thankfully, you can change it if you don't like the style or the color.
The Sims Medieval has popups with two options that your Sim can say; sometimes it really is choosing between a nice option and a mean option, but sometimes you can just choose what you like better and get the same reaction. One pirate quest has insult trees, where you're supposed to win an insult duel with a pirate, so both of the options are nasty. (Like any other Sim game there are also the pie menus in normal social interaction, which can include fairly specific things like "Joke About Dragons," "Imply Mother Is A Llama" and "Pontificate Poignantly.")
Portopia Serial Murder Case from 1983 may possibly be the Ur Example.
The Ace Attorney series uses this from time to time, usually in court, where you have to point out a murder method or decide something. Sometimes the choices are fake outs and you can only go in one direction anyway, which has led to at least one idiotic moment.
Just about every Visual Novel uses this, save for a few rare aversions or subversions.
The original PC versions of the When They Cry series is one such aversion. Only later in the series do choices get added, and this is typically a gimmick. The ps2 version of Higurashi no Naku Koro ni plays it straight, however.
Non-video game examples:
Excel♥Saga spent its fourth episode parodying a Japanese Dating Sim, and whenever a dialogue tree came up, the last option was always "Put it in".
In the Terminator 2: Judgment Day novelization, the T-800 also has a dialogue tree to select responses from. When Sarah Connor says that he looks like "handmade shit" when she tries to fix up his wounds, the T-800 accesses the dialogue tree and then comes up with the response, "So do you".
Played Up to Eleven in Real Life. When your character talks to someone, the possible response are endless. It follows the general pattern of "say nice, get nice," though this isn't always the case. Of course, the personality, hobby, mood, gender, orientation, etc. of the character you speak to influences the answers heavily.
Seriously though, when someone not knowing the local language gets a service job, they tend to have preprepared responses so as to be able to do their job despite not being able to communicate.
Hilarity can ensue when the person encounters a customer with an unprecedented question or response. The simplest example might be someone who understands "yes" and "no," but not "a little bit, please."
Call centres use these a lot, often to avoid having to give too much training - they just read the options off their screen, and pick what you say, leading to more questions. Hilarity Ensues if you go off script.
Fun to play with in shops, especially electronics "big chain" retailers where the assistant is just someone to serve, rather than knowledgable about the technical aspects of the item. A favourite is to buy a cheap cable for a digital connection, then wait for the assistant to recommend the expensive alternative. Then start asking questions about why a gold plated connectors on a cable is better. Point out with a digital conection you either have a connection/signal or you don't, you can't get a stronger/better or weaker signal. For bonus points start questioning the assistants knowledge of the PS3/TV/digibox/whatever, and wonder if he was as wrong on that as well.