Friday, July 27, 2012

How Much is Too Much Detail?

I've been playing quite a few older games recently.  Deus Ex, Thief, System Shock 2, Neverwinter Nights 2 and others have captured my attention for many, many reasons.  Just today, I tried to go back to a few more modern titles, and found myself running into a mental brick wall.

Specifically, that brick wall was the amount of detail on display.  The graphical jump of the newer games was noticeable, certainly, but I found myself surprised at how much re-acclamation I had to do in order to go back to enjoying the newer titles.  There's a certainl simplicity to these older titles, much of it the result of technological constraints, that I think current developers, whether artists or level designers, could learn much from.

Readability

Level design has never just been about creating great-looking environments, or even ones that are fun to engage with on a mechanical level - a fundamental component of it is in creating spaces that are readable for the player.  That is, they must be intuitive to understand even at a quick glance.  What does this actually mean in practice?
  1. Levels must have strong focal points.  Objectives and important objects should be placed in plain sight and difficult to miss for most players.  This is pretty standard stuff - lighting, colour, elevation, and more are all capable of highlighting important game objects the player needs to engage with.
  2. Levels must be understood at a glance.  Where things tend to break down, especially in games that feature highly-detailed environments with lots of props and interactive objects, is in throwing the player into a new situation and having the goal and the means to achieve it be immediately clear.  If we don't know what we're doing, or how to do it, a game can quickly become frustrating.
  3. Levels should make use of intuitive extra-game knowledge.  The best level designs will often mimic things that we understand in real life.  We know, through experience, how an office building floor is laid out, or how a series of city blocks connect to form a grid.  A level that deviates from conventions will often be difficult to understand and confusing to engage with, since players aren't just navigating a new space, but one that directly contradicts everything they know about how that space should be arranged.
Looks amazing!  Er... so where am I supposed to go, again?
As usual, these are not hard and fast rules for building levels - many developers intentionally break them, purposely confusing or misleading players.  Valve, for example, routinely do this in all of their games, especially the Left 4 Dead series, which purposely creates spaces that are cramped, cluttered, and difficult to read at a glance in order to stall players and leave them vulnerable to attack.  Horror titles also frequently create levels which deviate from real-world expectations, in order to trick players or createa  surreal sensation.  However, these are exceptions, and a game built of nothing but misdirection will grow tedious and annoying.

Visual Language

Most games, especially those with well-defined and distinctive art styles, tend to have consistent visual languages that they use throughout to guide the player both in playing the game and in using its interface.  The key to good art direction isn't usually just creating visuals that look good, but rather visuals that assist the gameplay and provide the player with sensory cues.

A lot of these are very simple things.  Most games, for instance, use a consistent font throughout the entire user interface, and will use the same-coloured text or the same icons in that interface to be readily readable by the player - a good interface will usually let a player go on pattern recognition and muscle memory after a minimum amount of time spent with the game.

However, consistent visual language extends well past user interface or other obvious examples - in my opinion, one of the keys to this that is often overlooked is in creating a palette of level artwork that designers can reuse and players can constantly refer to.  Just like different colours can be used to outline which enemies are tougher than others, visually separating less obvious interactive game elements also helps players make split-second decisions.

BioShock uses level art, right down to mundane things like doors and switches, to guide the player and make sure each piece of its levels are immediately and intuitively readable.
 What do I mean by this?  Take BioShock, a game with one of the most renowned and defined art styles to come out in the last generation.  Cutting past the pretty lighting, pixel shaders, and art deco styling, BioShock's visual direction succeeds because it adheres to a degree of consistency that extends from enemy designs all the way to the smallest environmental cues and details.

In BioShock, each gameplay element, whether it's an object central to the mechanics or an incidental environment prop, has one or at most two different looks.  The game, for the most part, has only two doors - large, vertically sliding metal doors that signify the boundaries of different level areas, and smaller, horizontally-sliding doors which signify smaller areas, like individual rooms.  The transitions between levels themselves (separated by loading zones) are almost exclusively large airlocks.  Water on the floor, useful for electrocuting enemies, always has a strong reflection visible even from a distance.

Could BioShock have had a hundred different types of door, each one perfectly suited to a given location?  Of course, and it also could have had dozens of brands of ammo dispensor.  The pretense of detail and realism is certainly compelling - but by limiting the palette available to level artists, Irrational Games created a game whose visual style was in direct service of not just the gameplay mechanics, but the needs of players in actually using those mechanics.  Once you've performed an action, interacted with an object a few times, it becomes second nature - and the key goal of play summarily becomes problem-solving, not mere navigation.

The Perils of Detail

When examining older titles like Thief and Deus Ex, it becomes obvious very quickly that these games are exceptionally readable.  A noisy, tiled floor in Thief can immediately be distinguished from a soft, quiet, carpeted floor.  In Deus Ex, ventilation ducts, often both enablers for tactical gameplay and safe havens, always use the same texture.  The simplicity of the visuals works so well even to this day because they are eminently readable; there is no room for misinterpretation because the levels are clean, focused and consistent.

As I mentioned above, earlier today I went back to a couple of other more modern titles.  The first was The Elder Scrolls V: Skyrim.  Although I'd put over a hundred hours into the game in the past, it was shocking to me how much time it took for me to get back into the swing of things.  Paths through the game world were difficult to read due to the extremely dense vegetation.  Discerning which objects in the environment were interactive, and which ones were worth interacting with in the first place took me an extra mental step or two.  Picking out enemies to fight was less about looking for familiar shapes, animations and routines, and more about scanning for movement, then focusing in to ascertain the source.

Games like Skyrim are visually impressive, but also visually cluttered to the point where it can be difficult to pick out anything at a glance.
It didn't take me more than an hour to get used to it - but it does highlight how the lack of a readily readable game world can get in the way of gameplay.  There are many, many situations throughout Skyrim where the only way to proceed in a given quest is to loot a certain chest, or read a certain book, or kill a certain NPC - and without the ever-present quest markers hovering over the important things, it's almost impossible to tell how to make progress in the game in any sort of visually intuitive manner.  These assists exist not because players are dumb and too thick-headed and ignorant to figure out where to go to finish the game - they're there because the only people who could intuitively navigate much of Skyrim are the developers who created the content in the first place.

The other game I went back to was Call of Duty 4: Modern Warfare, for a little bit of multiplayer gaming - and I learned very quickly that it was a far cry from Unreal TournamentCall of Duty's levels are mostly drab and monotone, making it very difficult to distinguish one area from another at a glance (though this improved in some of the sequels).  Many spots are thick with clutter objects and vegetation, making it very difficult to pick out individual players.  The constant stream of explosions, smoke and fire throughout the levels is disorienting and obscures other players, available routes through the level, and other important information.

Older titles like Deus Ex are visually fairly simple, but there is no ambiguity in interpreting its environments or scenarios.  No more pixel hunting?!  2000, here I come!
This isn't necessarily a bad thing, of course, when taking into account the fact that Call of Duty intends a degree of realism compared to some other shooters - target acquisition is intentionally a bit difficult, and the chaos of the battlefield can be hard to understand, precisely because the game's goal is, to a degree, to replicate the chaos of real warfare.  The challenge of Call of Duty doesn't just come from pointing and shooting, but from being able to cut through all the smoke and fire to understand the battlefield.

Even so, I found myself almost entirely relying on certain visual assists.  Without the little "X" that appears when firing at an enemy, it would be nearly impossible to tell you were actually hitting until the enemy was dead.  Without the coloured names over team members' heads, it'd be impossible to tell one black-clad, helmet-wearing man with guns from the next.  Without the grenade indicator on-screen and the distinctive "ping" noise one makes as it lands nearby, it'd be almost impossible to dodge them.  Unreal might not be realistic, but at least I can tell different players apart from one another! The chaos of Call of Duty may be intentional, true, but the reliance on all these user interface elements to distinguish them highlights that the focus on detail and realism is not necessarily conducive to good gameplay.

Closing Thoughts

As I mentioned earlier, I can't stress enough that a lot of these things aren't set in stone - sometimes making exceptions to the standards set, or intentionally creating a game without a degree of consistency, or one that is difficult to read at a glace by "obfuscation through detail", can actually work really, really well.  And, while I might have had trouble getting back into some newer titles, I don't want to paint a picture that they are difficult to play or confusing by any means.

Rather, I'd like this to be a cautionary message against creating detail in game visuals for the sake of detail, and realism for the sake of realism.  The increasing number of interface assists in most titles, coupled with the desire to continually push the bar in creating highly detailed, cluttered, rich game levels, just doesn't always work.

It might be a simple or even obvious message, but it's hard to play a game when you can't differentiate the important bits from the background scenery, and the result is that even (relatively) mechanically shallow games with simple, linear levels and mission objective markers around every corner can still feel cluttered and overwhelming in a way that actively goes against the freedom in gameplay that was engineered in the first place.
pit_door

Thursday, July 19, 2012

Of Shadow and Light: Thief

If there's one benefit to the Steam summer sale, it's that players like myself get to try out a lot of games that they missed out on in the past.  While for most players this might mean the hits from a year or two ago, that can also mean far older titles that this generation may not have experience with or have even played before.

Thief: The Dark Project is one of those games.  Originally released in 1998, and situated right in the middle of the "thinking man's shooter" trend defined by the likes of Half-Life and System Shock 2, Thief was a stealth game that pioneered advancements in AI, physics, graphics technology, and most importantly, was able to make use of its innovative features to introduce gameplay that had never been seen before (or, for the most part, since).

In this article, I'll be taking a look at some of Thief's successes, as well as why its sleek, stealthily efficient design holds up so well even over ten years after its release.

Building Blocks

In my opinion, the strongest games are always those which create systems of rules and interactions that allow players to experiment freely, to see the effects of different actions within those systems in order to come up with solutions to various problems.  While many games these days are created as scripted, linear thrill-rides built to entertain in the most bombastic fashion, Thief comes from, interestingly enough, the same school of thought that has spawned simulation and strategy games - that mode of design thinking that says "pull the player in a bunch of different directions simultaneously, and good gameplay springs forth."

Thief, is, on the surface, an extremely simple game - it's about getting to objectives in one piece by evading enemies.  Where Thief really differentiates itself is in all the different options it provides players, and the ecosystem that they live in.  While some titles will resort to fantastical representations of their mechanics in the form of magic, or sci-fi technology, Thief revolves wholly around two basis senses: sight and hearing, and the player's ability to manage being heard or seen by enemies.

By putting these two resources in conflict with the goal (get to the end of the level), Thief is able to pose incredibly challenging problems to players which are made complicated not by any pretense of depth in RPG-like leveling, or hundreds of weapons to choose from, but by modulating the player's ability to manage resources, through careful level design and enemy placement.

Thief was the first stealth game to stress the value of hiding in shadows, rather than just behind objects.
Visibility is the most obvious and most important resource for players to manage. Every enemy has an (invisible) cone of vision, although different enemies are able to see with varying effectiveness.  Being seen in Thief, while not tantamount to failure, is still a major problem and in most cases the player will want to avoid being seen as much as possible.  Vision must be managed in two ways:
  1. Light.  Light is everywhere in Thief, which is a big problem when you're trying to remain unseen.  Hiding in shadows is the fundamental action players will perform in Thief, and the vast majority of gameplay challenges revolve around either finding shadow or creating shadow.  The player is able to manipulate light and darkness through items like Water Arrows (to extinguish torches) and Fire Arrows (to light torches) - limitations on the player's quantity of arrows ensure they are indispensable, but precious.  Moreover, some lights can't be extinguished, which means that players, at some point, will always have to expose themselves - which leads to...
  2. Movement.  Movement is really where Thief's gameplay earns its complexity.  Control-wise, Thief is extremely simple - it controls identically to first-person shooters, but also includes leaning and the ability to perform two more advanced acrobatics - mantling ledges and climbing ropes.  Movement is in direct contrast with vision - moving makes it easier for enemies to spot the player, and light must typically be avoided while moving.  Moving more slowly offers more safety from direct line of sight, but moving quickly is generally safer when enemies don't have a direct line of sight.
If these two elements were all players had to manage, then gameplay would already be fairly complicated and interesting.  However, Thief also makes sound nearly as, and sometimes just as important as visibility.  Back in 1998, Thief had some of the most realistic sound effects and 3D sound positioning of any game, and like the dynamic lightmaps creating light and shadow, the gameplay took full advantage of this:
  1. Movement speed determines how much noise the player makes.  Whereas visibility only matters if enemies have line of sight, sound will alert enemies in a much wider radius.  Alerted enemies aren't just harder to avoid, they're harder to kill or knock out.  Therefore, not only does the player have to manage exposure by moving precisely and carefully, but the sound created while moving as well.  Certain routes in Thief require running to traverse, often due to the more advanced acrobatics required, and balancing sound created vs. the ability to reach a location more quickly becomes a common and compelling risk/reward element throughout the game.
  2. The surface the player walks on determines how much noise is made.  Walking on grass and carpet stifles noise and allows the player to move more quickly with more confidence, but tile, metal grating and other noisy floors require extremely slow movement to traverse, and even then there's no guarantee enemies won't perceive something.  Many, many environments take full advantage of this by mixing different types of floor surfaces in complex patterns, again posing a risk/reward dichotomy that often forces the player to pick between direct exposure in bright light vs. a noisy surface with patrolling enemies.
It goes without saying that most of these systems also help the player as well - being able to see enemies is more a privilege than one might expect, and hearing them, including their commentary, the surfaces they're walking on, and their 3D position in the world all provide the player with extremely valuable feedback - and obtaining that information can, in many cases, also put the player at risk, adding yet another layer of risk and reward.

Later levels juxtapose sound, light, and elevation, as well as complex patrol routes, to create challenging encounters.  In this one, the player must expertly time a series of movements between different guards, taking into account loud surfaces to walk on and a lack of shadows, to avoid detection.
Light and sound, and their relationship to player movement, are enough to make even the smallest of challenges in Thief interesting.  Movement in videogames is usually something we take for granted, and modern games have had different floor surface types, sound effects associated with movement speed, dynamic lights, etc. for years - yet in almost every game, it's entirely cosmetic.  In Thief, it is the game - and in the years since, there hasn't been a single stealth title that's been able to replicate the strength of the design or the implementation.

Putting the Tools to Use

With the basic mechanics out of the way, it's worth going into discussion about the level design.  Thief pioneered an open-ended style of gameplay which was more objective-oriented than the gameplay found in earlier shooters like Doom and Hexen, and drew a lot from System Shock some years before.  Thief's stages consist of sequential series of rooms, almost every one posing different gameplay challenges, which the player has a great degree of freedom in navigating.  Games like Deus Ex: Human Revolution today faithfully recreate the same design of branching paths leading to the same goal.

The strength of Thief's level design can be seen in its very first stage, a theft of a priceless scepter inside Lord Bafford's manor.  Immediately, the game opens with the player staring down the front entrance of the place.  In every other shooter, the obvious choice would be to barge down the front door and fight the guards... but thanks to a warning from the player character Garrett, and a quick death should the player ignore it, game teaches, in its very first challenge, that the frontal assault is not advisable.
This gate bars the most obvious entrance to the manor.  Later on, the player will see the gate from the other side, providing great feelings of accomplishment and progress.
 Instead, the player is encouraged to explore the streets around the manor.  Along the way, there are a variety of side paths, including a sewer system which the player can crawl through to gain some early extra valuables and a cache of equipment.  This sewer is by design rather confusing and maze-like, which teaches the player to keep a mental note of landmarks and sets the stage for many of the game's later environments, which eschew hand-holding and offer players multiple routes.  Its optional nature and the reward for exploring it also does a great deal to encourage players to step off the obvious path.

The first enemy the player faces is actually completely impotent - a drunk guardsman who stands in front of a locked door.  This encounter subtly teaches the player that there are a variety of ways in dealing with enemies - in this case, it's possible to either knock the guard out and take his key, kill him, or pick his pocket and sneak in.  As he's no threat, there's no danger of the player making a mistake in the early stages (but that trend in enemy effectiveness will change very quickly).

Once the player gets inside the manor, challenges gradually ramp up.  The first areas are relatively straightforward, and teach the importance of staying out of sight by rooms that emphasize light and shadow, encouraging the player to make use of them.  Shortly after, different floor types are introduced to demonstrate how different surfaces affect the noise both the player and guards make - with the player first observing this in the enemies themselves by hearing their footsteps change, rather than allowing the player to run ahead only to find him or herself in a combat encounter with newly-alerted enemies.
Thief provides a great degree of room for creativity and optional challenge.  This room, for instance, allows the player to remain unseen and unheard by very carefully timing movements and jumps, almost platform-style.
The final challenge of reaching the scepter is actually fairly devious for players concerned with actually being stealthy, but serves as a great final lesson that prepares the player for the rest of the game.  On the top floor of the manor, the floors are decorated with tile, which produces a lot of noise, and a heavily-armored guard patrols.  The tiled surface is broken up by patches of much quieter carpet.  The player's goal, the manor's throne room, is locked, and the key can be obtained either by braving the loud corridors or by taking out the guard.  Once inside the throne room, a similar challenge of carpeted and tiled floors awaits, but this time, the single stationary guard is much harder to avoid.  Crafty players, in both instances, can actually "ghost" the entire upper floor by precisely jumping between patches of carpet.  Either way, navigating the manor to reach the scepter is a rather involved and challenging affair for an introductory stage, but it ensures that players will have fully grasped the game mechanics and now will be ready for greater challenges.

Variable Challenge

The last thing that still makes Thief an excellent game to this day is the way that it handles challenge.  Most games have a set difficulty curve that is designed to fit a median skill level, usually erring on the easier side - I've heard more than once that it's a good idea to "make a game easy, then make it even easier."  Thief does away with this by providing a multi-tiered approach to difficulty levels:
  1. Higher difficulties reduce the player's resources.  Rather than give the AI severe handicaps, Thief reinforces the stealth gameplay by making resource management, including both health and items, more important, as there's much less room for slipping up and wasting supplies.
  2. New objectives.  Playing on normal won't give you the full Thief experience.  In most missions, actually escaping the level is omitted, with a simple cut to the summary screen occurring once the main objective is complete.  When played above normal, many missions have secondary goals that appear, such as special hidden loot to find, or contacting other characters during the mission.
  3. Extra loot.  Players who scour every nook and cranny of the game levels will walk away with more loot, and summarily, more money to spend between missions on more and better gear.  There's greater risk in exploring the whole level, but the cash usually makes it worthwhile.
  4. Multiple gameplay options.  The open-ended emergent gameplay of Thief is itself a way of regulating difficulty.  On the normal setting, combat, while challenging, is a viable solution in many cases, ensuring that even if players can't sneak through the level, they can still hack and slash through.  Pure stealth is the hardest approach, of course, and the brilliance of the level design only becomes apparent when playing in the sneakiest way possible.  Most players will stick with a mix of violent and non-violent means as appropriate to each situation, but they are never forced into one or the other.
  5. Advanced techniques.  Although many of the game's levels are labyrinthine, most are straightforward to actually get around, and most challenges can be solved by knocking out an enemy, picking his pocket, etc.  Players who spend more time with the game, however, will go to appreciate other aspects of it, like its physics simulation, which allows the player to pick up and throw or drop objects, and the new opportunities they provide for solving problems.  Stacking crates, throwing bottles to distract guards, and more expand the fundamental options available.
The reason Thief still lives years after its release, not counting its extremely dedicated modding community, is that players are still looking for ways to optimize their routes through levels, to complete them more efficiently, and to achieve that vaunted goal of ghosting the entire game on the hardest difficulty.  Most players will never do this, but the game systems are flexible and rewarding enough to not just accommodate, but invite experimentation and replays.

Closing Thoughts

I first played Thief shortly after its release, and I admit, at that age it wasn't quite the game for me.  As I've grown older, I've appreciated the game more and more, and it ranks as one of my favorite titles.  Taking a trip down memory lane today wasn't just nostalgic and fun, but it was highly informative as well, as the strength of the design shines through despite the dated visuals.  For all the great graphics and art direction we have today, Thief is one of the few games that uses every bit of its technology to enable significant new gameplay possibilities.

It's also a shame that, since Thief, there really hasn't been any other game like it.  The sequels in the series have certainly delivered, but developers chose to embrace the action angle of the stealth-action genre in the years following Thief, as well as the more accessible third-person perspective.  Perhaps a little too cerebral and slow-paced for broad audiences, and its contributions to gaming slowly faded over the last 15 years, Thief's unique simulation-style gameplay still remains largely unmatched.

Tuesday, July 3, 2012

Nothing Human: Creating More Convincing Conversations

Videogames are, generally speaking, about a few simple interactions.  Fighting is the one that undoubtedly shows up most often, but of course, there are plenty of other sorts - racing cars, playing sports, and so on.  But one thing that developers have yet to really master is something which is arguably far more pertinent to our interests as human beings - "simply" talking with other people.

There are all sorts of distinct challenges when attempting to simulate conversation.  Most games have distinct failure and success states, so dialogue has to be able to fit into our preconceived rules about winning or losing the game.  It has to give players a feeling of reactivity, otherwise it comes across as unnatural and stilted or even non-interactive.  Although there are manifold ways in which developers attempt to circumvent these problems, few are ever really been successful in creating dialogue interactions that feel realistic and believable.

In this article, I'll be breaking down some of those challenges in more detail and providing a few examples of techniques used to create compelling conversations, as well as a number of recommendations that can be used to approach tired dialogue systems from new angles.  Although I use role-playing games almost exclusively as examples here, it's only because there are so few examples of other games, especially in the mainstream, that revolve so heavily around conversation

The Uncanny Valley of Dialogue

Although the much-abused term uncanny valley is almost always used in the context of graphics when it comes to videogames, it's in dialogue where the uncanny valley becomes most obvious.  Just think about all the times you've been playing a game and a character's said something that doesn't make sense for a certain situation.  Perhaps you heard a dialogue line repeat itself.  Maybe a line was even cut off mid-sentence in favor of another one.  Or, after your first play-through of a game, maybe you found that most of the conversation options all caused characters to respond in the same way.

This goes doubly true for the player as well.  Even though games will often provide radically different choices in dialogue, or allow for multiple lines of inquiry, those lines always equate to simple choices between A, B, and C - there's little in the way of nuance and expression.  In Mass Effect, I can't choose to say a line in a cocky manner, or a respectful manner, or a snide one - I have to choose between the options given to me, and if I'm not given an option I like, then I'll have to pick another one.  For all those dialogue choices out there, a lot of time could be saved by realistically boiling everything down to the essential choices.

Even when we're given the option to choose the tone of our replies, the meaning can never stray from what's explicitly defined by the developers in advance.
The reason for this is obvious - short of creating some sort of super-intelligent AI to parse text and provide responses that make sense in context, and then coming up with technology to voice-act those lines in real-time, it's pretty much impossible to have dialogue that is truly adaptive to what the player can say.  Dialogue content is completely finite.  Although many interactions can be governed by sets of rules (wherein we abstract our conceptions of reality), speaking to another human being is something that is not so easily predicted.  People have personalities, they make rash and unpredictable decisions, they let emotions guide them.  Think back on all the times, even just today, when you said or did something based on impulse - while there might be some rules behind how you behave, they're certainly not things that you can divine, and you likely know yourself better than anyone else!

While we've had years and years of training to abstract activities like violence, and others, such as a football game, can be understood in terms of the rules governing the sport and simple approximations of physics, we have little understanding of other people, and even if we get to know someone very, very well, we can't predict complete strangers - in other words, the same rules don't apply.  Most videogame content works by producing sets of common rules that different actors can interact within - in a shooter, you interact with the world by shooting at enemies, who behave in predictable and finite ways no matter how many you fight; in a racing game you interact by piloting a vehicle in competition with others to reach a final point - but that doesn't work very well for talking.

Approximating Humanity

The first solution to this problem is to create a system for interacting with characters that deals less with providing highly detailed content, and more with content that is highly reactive to the player's input.  Necessarily, this will result in a dialogue system that is more approximate, but on paper, does this seem like such a bad idea?  After all, we already accept a great deal of approximation from videogames.  We understand that quips like "low on ammo!" serve as auditory feedback on another game mechanic, and we also accept that, under the hood, the game only has so many lines available to offer.

Smart developers know how to space out these lines to get the most mileage out of them - such as recording 10 different variations on the same line and making sure that players hear repeats as little as possible.  With a smart implementation, it's impressive how often players' brains will trick them.  We don't have extremely long-term memories for most things, so creating dialogue content that exploits the limitations of short-term memory will do a lot of the work for them.  But when it comes to more significant, memorable dialogue, that approach quickly becomes useless as long-term memory takes over.

There's really only two solutions to the problem - either create a dialogue system wherein most dialogue only plays once, but some will repeat indefinitely based on the needs of gameplay, or create a dialogue system wherein the amount of available responses increases dramatically.  Specifically, this means building a set of rules just like any other for the game, ones that approximate human interaction, and provide gameplay flexibility, even if it means giving up the "immersion factor."

Dialogue in Morrowind lacked the emotional resonance that unique responses could provide, but made up for it with huge amounts of detail and universal mechanics that determined how individuals reacted to the player.
The latter solution used to be very common in older role-playing games.  The Elder Scrolls series, up until fairly recently, used keywords to simulate paths of inquiry.  Players could have a list of ten, twenty or more inquiries, and would largely receive the same responses, with variations for specific cases (like plot-advancing dialogue, or minor variations such as changing pronouns and gendered terms around).  In Morrowind, for instance, most characters would recite the same lines over and over again, but mechanics took over - a character's individual reaction modifier would change based on the player's behavior (maybe asking about a taboo subject would net you a -20 reaction penalty), and racial or cultural background would also affect what a person could offer information on (so asking people about events on the other side of the world would rarely be worthwhile).

The big issue with such a system is that, now that you're dealing with a ruleset, suddenly designers and programmers have to start thinking about dialogue in terms of gameplay rules.  No longer can conversations be about conveying lots of unique emotions and subtleties to the player - now they're about cause and effect, winning and losing - and have to be crafted with that in mind.  And, like any game, those rules have to be consistent, predictable, and simple enough to understand.  By effectively turning dialogue into a mini-game, it becomes subject to all of the same constraints any other game is.

Dialogue by the Tree

Dialogue trees are a staple of role-playing games as well, and by far the most popular way to simulate conversation.  Dialogue trees, true to their namesake, take the form of a number of topics of inquiry, which then branch out into more paths.  For example, a dialogue tree structure might consist of: general inquiry -> clarification -> opinion, with the final option taking the player back to the "root" of the conversation.

Obviously, developers can do a lot with dialogue trees, and games like Planescape: Torment are testament to that, with thousands of unique lines of dialogue and dozens of paths of inquiry that, in themselves, make up much of the gameplay.  At the same time, however, the key limitation becomes abundantly clear: while you can take a few shortcuts with a dialogue tree format, pretty soon you're going to end up with huge, sprawling conversations.  The content bloat mentioned earlier is felt very quickly when using dialogue trees, and if players notice too many shortcuts being taken (like identical responses to two radically different dialogue options) then the sense of realism that dialogue trees usually go for is completely shattered.
 
Despite the bloat, however, it's clear that dialogue trees have a big advantage - they do a much better job at simulating the act of conversation.  Even if you need (mostly) unique lines for every inquiry the player makes, the big benefit of that is that characters can have much more personality, the player is able to express an opinion in more nuanced ways, and, most importantly, that the mechanical side of dialogue disappears.  While there's always going to be a binary yes or no choice, many games do an excellent job of obscuring exactly where the variables in conversations are flipped - Dragon Age: Origins, for example, will show the amount of influence earned or lost after a conversation, but deliberately hides what dialogue options actually affect it, to better simulate the act of talking to a person rather than picking responses from a list for best effect.

Dialogue trees can provide much more detail than almost any other dialogue mechanic short of a graphic novel, but the amount of writing required can become prohibitive to presentation.
Additionally, the reuse lines as "cheating" on the part of the developers might be a little unfair.  Usually, it's actually quite acceptable to reuse responses and add separate lines in that help redirect the conversation.  Most players never really notice these - next time you're playing a dialogue-heavy role-playing game, take note of how many times you hear connecting statements like "anyway", "however", "meanwhile", and so on - in almost every instance, they're being used to disguise points where the conversation has branched and needs to re-converge.  Once you pick up on this, it's surprising just how scripted many conversations really are, but so long as there are enough unique lines to keep the illusion going, it works splendidly.

There's also the player's own emotional impact and investment to consider.  Gamers are usually not developers, and they're not going to be keen to the tricks and shortcuts used - they're often in a very different mindset when playing games, enjoying the content as it's presented to them rather than fussing over the details or looking for holes to poke.  Therefore, as much as I want to complain about Commander Shepard's heroic speech influencing absolutely nothing in Mass Effect, I have to admit that, as a player, it's still pretty cool to be able to give that speech in the first place - to me, it feels like a real decision, and the way that it influences the tone of the narrative can't be denied.  Even if it doesn't really matter to the game whether Shepard's an idealist or pragmatist, it matters to me.

Closing Thoughts

The unfortunate fact is that there are very few other ways that developers have actually handled dialogue - although I could bring up text parsers, they're really not much different from the keyword system mentioned above, except that the possible inquiries are kept ambiguous.  For all the games industry has managed to so effectively simulate the act of killing another human being, or driving a car, the more complex and subtle, less predictable and deterministic act of talking to another person is something that's still up in the air.

That said, there's a few ways that existing dialogue systems can be enhanced to produce conversations that feel more natural and realistic:
  1. Abandon the UI.  Sometimes, it's better to produce results by getting the player to actually do something rather than picking options off of a list or typing them into a dialogue box.  A great example of this can be seen in Half-Life 2, where Alyx Vance will react to all the things the player can do in the game world - they're not deep interactions, sure, and the game is a shooter so there's little meaning behind them as far as gameplay goes, but there's something far more satisfying about using the tools available in one's arsenal to provoke a response rather than selecting "(Shine flashlight in Alyx's eyes)" in a menu.  The upcoming Naughty Dog action game, The Last of Us, looks to be taking this model to new heights.
  2. Emotional impact doesn't mean detail.  It's a common misconception that players need voice acting, an orchestral score and Hollywood-style direction to connect with the characters in games.  Our brains are willing to fill in an exceptional number of gaps in presentation, and sometimes the most engaging experiences are the ones that exist in our own heads rather than in code.  The emotions that players bring to the mechanics of a game are far more potent than the ones that writers try to squeeze out of an audience via sympathetic techniques.
  3. Remember what the player's done.  This is a little thing, but one of the key ways to make characters feel real in a game is to make them reference past events to provide a sense of continuity to the world.  These don't have to be dialogue choices either - one of Deus Ex's most remembered moment is Paul Denton scolding or praising the player depending on the level of lethality used in the game's opening mission, while other characters have the opposite reaction.  This simple distinction, which ties in with the broader mechanics of the game and was probably tracked in all of one or two variables, does more to draw the player into the game than all the expensive cinematic sequences in the world.
As usual, thanks for reading, and please feel free to leave comments below!