Definition: Verisimilitude


The quality of seeming to be true, of resembling reality

Why is Wii Bowling like a Hemingway novel? (Beside the fact that they are each made better by adding alcohol.) They both benefit from the effects of verisimilitude. Authentic characters and believable dialog enhance the reader’s engagement in a story; they do not call attention to the fact that they are fictitious by violating our expectations about what might really happen. In the same way, the way the player’s movement in Wii Bowling matches the form and timing of real bowling avoids the awkward break with reality many people feel when playing video games.

Verisimilitude is important for many aspects of game design. Poorly tuned physics systems, bone-headed AI behaviors, inaccurate collision tests, unrealistic lighting, and scores of other common problems all result in a game feeling “off” or “fake”. That is why players can complain about an “unrealistic” space marine pulse rifle; even though no such thing actually exists, they have an intuition of what it would be like if it did exist.

Teach me!

Exactly like this...

However, nowhere is a lack of verisimilitude felt more strongly than in poorly designed controls. If an in-game action clashes with the input method to which it is mapped, it will always break the player’s flow and they will never be comfortable with the controls. Ideally, when the player is engaged with a game, the controller fades into the background and they are no longer aware of it, but an awkward or discordant control scheme is a constant reminder that they are playing a game. Here are some guidelines to avoid mismatched mappings:

  • The duration of an input should match the duration of the action. If a single button press is mapped to a melee attack, the animation for the attack needs to be short and responsive, just like the button press. If the animation needs to be longer, it should require several presses, or a press and hold, that takes roughly the same amount of time for the player to execute. Rapidly tapping a button during a grapple is a bit cliché, but it works because it extends the duration of the input to match the onscreen action.
  • Do not map discrete actions to analog inputs. A game where the player initiates a melee attack with the throw on a thumbstick is using an analog input (the range of motion of the thumbstick) to trigger a discrete action (punching a Triad thug in the face) which makes the player feel detached and removed from the action. This is often described as “soft” or “unresponsive”.
  • Do not map unrelated actions to integrated inputs. The D-Pad is not a set of four buttons, no matter how many games treat it as such. It physically represents four cardinal directions, and it is virtually impossible for a player to get comfortable with treating them separately. In the same way, a thumbstick is not a an arbitrary number of discrete buttons arrayed in a circle, and using them that way will prevent most players from engaging completely.
  • Do not use two-step inputs for single-step actions. The easiest way to add inputs to the controller is to use chords, two buttons pressed at the same time. This works great for “zoom” and then “shoot” because it is a two-step action, but is jarring when used for actions that appear to happen all at once.
  • If an action cannot be mapped to the controller, it should be cut. This is the hardest rule, but the most important. Some actions conflict with one another on a fundamental level, and though it may be tempting to cram them both on the controller, the game will suffer for it. It’s better to have a single action that players can execute confidently and competently than multiple actions that are confusing and cluttered.

In Anticipation

Most of the time involved in playing any game is spent waiting.  In a turn based board game each player waits for the others in sequence.  Even in a timed chess game the actual portion of the game spent moving a piece from one square to another is much less than the time spent waiting for your opponent or considering your own move.  A play clock in football allows for 40 seconds of inactivity between plays that often last less than 5.  A  tennis match can stretch for hours, with time eaten up not just between volleys, but as one player waits for the ball to be returned (or not) and then moves into a new position and waits for the fraction of a second it takes the ball to reach him.  Even in an intense bout of Street Fighter, the actual portion of time spent pressing buttons and taking meaningful game actions is suprisingly low.

Take all the time you want

It could be argued, then, that most of what we call gameplay consists of waiting.  Not passive, disinterested idleness, but active, focused anticipation.  One key to understanding why a game is fun lies in analyzing the type of anticipation it creates and how a player experiences that expectant state.

Anticipation of the Unknown

The player has no idea what might happen next.  While every experience begins with this form of anticipation, it is the least desirable.  The power of the mind is its ability to creatively construct predictions, of the future, of the underlying nature of reality, of the internal state of another person, and when it starved of information it becomes inactive.  “Anything can happen” is not a statement of possibility, but of unintelligible chaos, and it is a very uncomfortable place to be.

Anticipation of Result

Heads or Tails?  Rock, Paper or Scissors?  Red or Black?  Who wins, who loses?  This type of anticipation occurs when we have a stake in the outcome, but no control or predictive insight.  We are wired to make sense of the world, and when something resists, it itches.  In the absence of actual patterns, people invent them, which is the basis for superstition and our utter inability to intuitively comprehend randomness.  Engaging curiosity in this way is a useful tool, especially if failure is not punished, but if it never pays off it turns to frustration.

Anticipation of Evidence

We know the hero is going to save the day and get the girl.  Screenwriters understand that their audience wants a comfortable trope and if they violate this tacit desire the focus groups will force a re-write.  But we don’t know how, when everything looks impossibly bleak, the hero will turn the tables.  We are anticipating the moment where the pattern is revealed, the hidden trump card appears, and our faith in the Hollywood formula is proven correct.  This kind of anticipation is present in puzzle games where we know there is a solution, but we aren’t sure what form it will take or how we will discover it.  Nothing is more infuriating than a puzzle we know we are intended to solve, but can’t.

The World before Walkthroughs

Anticipation of Action

This is the primary form of anticipation found in games.  The player knows that soon it will be their moment to act, has a model for making predictions, and is excited to test that model against reality.

  • Queued Action – The simplest form of anticipated action.  The player knows what they intend to do and are merely waiting for the opportunity to execute.  As soon as the game begins, I will move my Queen’s Pawn forward two spaces.
  • Queued Reaction – Preparing to respond to an event, either in the environment or initiated by another player.  Because there is only one prepared action, the response time will be as short as possible.  The instant they stick their head around the corner, I’m going to open fire.
  • Multiple Queued Reactions – Mentally preparing for multiple possible events and focusing on distinguishing between them quickly.  If the ball comes to me, I’ll catch it.  If it goes to the outfield, I’ll be the cut-off.  If it goes toward first base, I’ll cover second.
  • Inductive Prediction – Trying to guess what an opponent will do and act preemptively at the right moment.  (David Sirlin calls this Yomi, or “knowing the mind of the opponent”.)  I bet they are going to try a jumpkick, so I’ll throw my fireball to catch them on the way up.
  • Deductive Prediction – Using knowledge of a player’s available actions to reduce the number of reactions that must be prepared.  He’s carrying the sniper rifle, so I bet he isn’t going to rush my position.
  • Forced Prediction – Performing an action for the sole purpose of forcing another player to make a predictable response, with the intention of capitalizing on it.  In fencing this  is called a second intention and happens when you are driving an opponent to react to your attacks instead of taking the initiative themselves.  I’ll fire at his feet with my rocket launcher, which will force him to jump into the air and leave him unable to dodge my second rocket.

One important aspect of game design is intentionally inserting gaps in the action to allow for the desired anticipation.  A simple game that has too few possibilities or happens too slowly will fail to fill the time between actions and become dull or predictable.  A game that is overly complex or happens too quickly will cut short the player’s anticipation and feel out of control or chaotic.  Giving the player control over the pacing may encourage them to over-think their actions.  A small change in the cadence of a game, or providing more or less predictive information, is often enough to change type of anticipation, which is a powerful tool for adding gameplay variety.  Understanding and tuning anticipation is crucial to crafting a fun experience, because once anticipation is gone, boredom sets in.

Reciprocal Difficulty

Push on the wall.  This is not a metaphorical encouragement to seek innovative solutions.  Literally, place your hands against a wall and give it a shove.  Now, assuming that you are not working in a cubicle, you have just experienced what physicists call a normal force.  The wall pushed back against your hands with the exact same force you used on the it.

Purchase Gotham City Mutual's Superman Insurance!

Unless you have superhuman strength... Sorry Superman

One of the prerequisites of a flow experience (as defined by Mihaly Csikszentmihalyi in his seminal work Flow: The Psychology of Optimal Experience) is that the difficulty of the activity roughly match the ability level of the participant.  If it is too easy, they will not become completely absorbed and lose themselves in the activity.  If it is too hard, they will become frustrated and unable to make continual progress.  Balancing between these two extremes is the responsibility of the game designer, but often there is not a single setting that works for every player.

One solution is to allow each player to choose their own difficulty level before starting the game.  Unfortunately, the vast majority of players simply choose the default option in their haste to start playing.  Very few players will admit to needing to play on Easy difficulty, and even good players may be too intimidated to start out on Hard.

Every answer seems insulting

I'm tough like week-old bread

Another solution is to dynamically change the difficulty of the game based on an ongoing evaluation of the player’s skill.  But in practice, this automated system usually destroys the intended pacing of the game.  A well-designed game will have periods of less challenge that lead to a more difficult section, building and relieving tension through the gameplay.  A dynamic difficulty system that is too sensitive will add wild fluctuations on top of these natural curves, obscuring the overall effect and flattening out the tension.  One that is tuned to adjust more slowly will often react to the easier segments by ratcheting up the difficulty at the same time that the designer is increasing it for pacing reasons, resulting in an unintentionally large difficulty spike.  Not to mention that the player’s sense of accomplishment will be undercut if they realize the game is “letting them win” by compensating for their low skill levels or “cheating” by getting harder as they get better.

A better solution is to learn from the wall’s normal force and design mechanics that match the player’s skill with reciprocal difficulty.  (Calling this technique normal difficulty seemed confusing.)  In a game with reciprocal difficulty, the more aggressive the player is, the harder the game gets.  But when the player becomes overwhelmed and stops pushing, the game immediately gets easier.  This allows players of all skill levels to be challenged; a good player will play more aggressively until the game gets hard enough, and a less skillful player will proceed at a slower pace until the game gets easy enough.

Examples of reciprocal difficulty mechanics:

  • Recharging Health – If a player is too aggressive and tries to fight too many enemies, they will die quickly, but as soon as they withdraw from combat their health recharges and they can proceed more carefully.
  • Defensive AI – Enemies that are much more effective when fighting from a defensive position are naturally more difficult when the player is pushing hard against them, but allows a timid player to pick them off slowly without putting pressure on them by chasing them.
  • Optional Objectives – Puzzle games that can be solved simply by any player, but have optional collectibles or rewards for completing a puzzle in fewer moves provide more challenge for better players.
  • High Scores – Any mechanic that encourages players to play for a faster time or to score more points is better able to satisfy a variety of player skill levels.
  • Character Leveling – If a player is having trouble with a difficult section, they can make it easier by earning experience and making their character more powerful.
  • Press Your Luck – The player is allowed to periodicaly save their progress or reduce their difficulty level, like going back to town in Diablo or repairing their aircraft in Crimson Skies, but good players will take this option less frequently.

Exaggerated Causality

This is one of my favorite screenshots of all time:

...nothing but net

Elaborate by Dewski14

In one frame, this screenshot tells an epic tragedy worthy of Sophocles himself.  Red Sniper, furious at Blue Man for stealing the attentions of his bride, Grenadina, confronts him in an alley behind the cathedral.  After a heated exchange, the jilted lover fires a single shot at his rival, who ducks out of the way, and the hateful bullet ricochets into the heart of his beloved, who was hastening to tell them they were actually brothers, separated at birth.  The story can be told because the causes and effects are so cearly linked; by exaggerating the causal relationships and drawing out their interactions, a confusing or seemingly random event can be transformed into a dramatic moment.

At a basic level, a game can be interactive only because it is a simulation, a systematic collection of cause and effect relationships.  It doesn’t matter if the world being simulated is rigid shapes dropping into a well, a jungle teaming with Jurassic wildlife or a city populated with tiny citizens, it’s the cause and effect nature of a simulation that allows players to make predictions, develop skills and play the game.  Some game simulations have explicit causal relationships.  “If you pass “Go” then collect $200 from the bank.”  Others try to approximate the real world, including the complex cause and effect events, with more or less success.  Unfortunately, the connections between causes and effects that are obvious in the real world are often difficult to track in a game, making them unnecessarily hard to understand and master.

Like finding a barrel in a haystack

The "Where the %@$# Am I Getting Shot From?!" Effect


Linking Cause and Effect

The best way to increase the intelligibility of your simulation is to increase the strength of the link between cause and effect in the player’s mind. 

Don’t Poke the Lizard Brain.  The human brain is not like a computer; it doesn’t have a lot of computational horsepower that can be applied to arbitrary problems.  What it does have are highly specialized neural circuits designed to perform a single task very efficiently.  Just like your graphics card is specifically made to render 3d scenes, there are parts of your brain devoted to almost every function you need to operate in your daily life.  There are circuits for determining the direction a sound is coming from, circuits for reading the emotions behind facial expressions, circuits that use shading to determine the shape of an object, circuits for predicting the path of a falling object, and countless other abilities we rarely notice we have.  The problem is, these circuits are so finely tuned for reality that the slightest deviation in a game simulation disorients them, destroying the player’s suspension of disbelief.

So, if a grenade explosion sounds like it is coming from the wrong place, players won’t understand that the grenade is what killed them.  If a character’s mouth doesn’t move right, instead of conveying the emotion of a scene they enter the uncanny valley.  If the lighting on an object is incorrect, or the physics system doesn’t make it behave accurately, players will not be able to predict how it will move or how they should react.  If players are constantly confused by what is happening and unable to describe the cause and effect relationships in a game, it is often because the simulation is off, even by a small amount, and must be tuned properly.

Create a Visual Connection.  The connection between cause and effect can be reinforced with simple visual elements.  If a blue-green gun fires a blue-green projectile that explodes with a blue-green explosion that leaves a blue-green decal and causes the player’s screen to flash blue-green, they will probably be able to connect the dots.  Another technique is to conserve the momentum of the cause in the effect, so if the player is melee attacked by an enemy charging from the right, throwing their body to the left in the direction of the attack helps link them in the player’s mind.  If a certain spell causes an enemy to become confused, use the same little stars on the spell icon that are circling the confused enemy’s head.  If one character is using mind controlling powers on another, actually draw visible waves of telepathic force between them.  If an ancient artifact slows down anyone standing within 20 feet of it, attach a visible effect that extends 20 feet to indicate the range.

Avoid False Causes.  It is also important to avoid creating false connections in the player’s mind between unrelated events.  Entire lobes of your brain are devoted to finding patterns, and sometimes the unfamiliar experience of playing a game puts them into overdrive and your mind doesn’t just recognize patterns, it invents them.  “I swear, every time I hear the sound of the timpani in the background music, I take damage.  I must find a way destroy the percussion section!”  Often these coincidental connections are difficult to predict, but they can be avoided by removing superfluous sounds, effects or actions that are not related to any game mechanic.  Fires or explosions that are purely for dramatic effect, but can’t actually hurt the player.  Enemy animations that look significant, but are actually just random variations on a walk cycle.  Environmental features that stand out, like switches or doors, but are merely cosmetic.  All of these are prime candidates for false causes.

Temporal Separation.  One of the most effective ways to help players connect a cause to an effect is by slowing it down.  If a grenade causes a vehicle to explode, delay the second explosion by a fraction of a second.  If flipping a switch causes a gate to open, slow it down so the gate takes several seconds to open completely.  If a headshot does more damage to an enemy, exaggerate and elongate their reaction so it is clear that something unusual is happening.  These delays and exaggerations help the player perceive the two events as separate and sequential steps in a process.  When two events are simultaneous, it is difficult to tell which one is the cause and which the effect, or even if they are related at all.   But a repeated sequence of events is easily recognized and understood. 

Oh, that's what happened...

Call of Duty's Kill Cam delays and replays the cause of your death

Add Intermediate Steps.  If I punch my younger brother and all the sudden I can’t sit down without wincing, I am unlikely to connect the two events.  However, if punch my younger brother, and then my Mom yells at me, and then I have to wait for my Dad to come home, and then I have to go get the leather belt from his closet, and then bring it back and “assume the position” I will probably learn the cause and effect connection.  At least after the first few dozen times.  Sometimes, the easiest way to make a connection more noticeable is by adding intermediate steps to the sequence.  Two events happening in the same order might just be random coincidence.  Five events happening the same way every time is probably not.

Exaggerating causal connections not only helps players learn how to play a game, but it increases the dramatic context of their actions.  It will allow them to construct stories instead of just experiencing a series of events.  And it will make the game more appealing to people that are just watching a video on YouTube, drawing in new players.

Definition: Game Mechanics

Game Mechanic

A single constraint on the possible gameplay actions that determine a part of the player’s experience.

According to our working definition of gameplay, the purpose of a game mechanic is to constrain a game’s interactivity so that it guides the player toward a fun experience.  Tuning these contraints is one of the most important game design processes.  However, in order to tune game mechanics, it is necessary to understand what mechanics are and how they combine to form gameplay.

First, let’s look at how a single game mechanic constrains the possible actions a player can take.  Often these constraints are explicit rules like “If the King is put in check and cannot legally escape, the king is checkmated and the game ends in a loss for that player.”   Sometimes they are limits enforced by the simulation; there are some gaps that Mario can only jump while running.  The most important constraints are usually determined by the game’s control scheme.  After all, the player can only perform actions which are mapped to available inputs.

Another common type of constraint is the player’s objective in the game.  For instance, a goal in Pac-Man is to eat all the dots.  This limits the player’s behavior because any interaction that does not involve eating dots is irrelevant to the game.  This mechanic divides all the entire spectrum of possible actions the player can take into two halves, actions that are permited and those that are prohibited.

More DoTs!  More DoTs!

Pac-Man suffers from OCD

Game mechanics guide the player experience by removing some alternatives and emphasizing others, but by itself, a single game mechanic is not a game and cannot lead to a fun experience.  In fact, a single game mechanic by itself is barely even interactive.  With only one constraint, there is only one option.  There is no room for choice or skill or expression.  To demonstrate this point, I built a “game” based on a single dot-eating game mechanic.


(My free Flash host can no longer keep up with demand, please click this link to load the example.)

In order to actually define an experience, game mechanics must be placed in opposition to one another, much like the legs of a tripod.  That way instead of creating a single boundary (and therefore no choices) they create a region of interactivity for the player to operate within.  This is what Will Wright calls a possibility space.  It is the sum of all the potential gameplay experiences, sort of the wave function of game design.
Triangle Man hates Pac-Man, they have a fight, Triangle wins

Or maybe the Triforce of Game Design?

Definition: Affordance

Affordance  (Also:  Usability, Discoverability, Intuitiveness)

The quality of an object or environment that allows a Player to intuitively discern and perform the gameplay action associated with that object or environment.

In his most profound philosophical work Being and Time, Martin Heidegger makes a distinction between two types of attitudes that we can have toward an object.  First, an object can be “present-to-hand”, which means that it exists and we can observe it and theorize about it.  Heidegger claims that this is an uncomfortable mode for us, that it is inferior to the more natural second attitude where an object has an immediate purpose, which he calls being “ready-to-hand”.

Imagine you are walking through a Home Depot and see a collection of hammers hanging from pegboard in the tool section.  Let’s say you are an English major and you have never seen a hammer before.  You might assume that you had stumbled into an unusual art gallery and start admiring the variety of colors and shapes the artist had created.  Clearly they are a phallic representation of our patriarchal history…

In this example, you would be treating the hammers as if they were “present-at-hand”.  In a game, every time the player is forced to stop and think about the possible actions an object affords they are forced out of their flow state.  If this happens too often they will never be able to relax and enjoy the game.

Killer Queeeeeen

Chess - A terrible example of percieved affordance

Now imagine you are in a burning building and the only exit is blocked by a flimsy plywood door.  This time when you see the hammer on the wall you do not perceive it as an object, but as a tool with a clear purpose.  There is no hesitation because there is no analysis.  The hammer is “ready-at-hand” and that door is “ready-to-smash”.  There is no break in flow because both the hammer and the exit door have clearly perceived affordances.

This is especially important in games, because the player cannot even begin to play until they understand what actions they can take.  The faster they can understand what is possible, the earlier they can get past the theorizing state and into the flow state of proper play.