He's about to have an experience he won't forget!

Put to the Question

If you want to learn something, read about it.  If you want to understand something, write about it.  If you want to master something, teach it.

– Yogi Bhajan

Successful designers are those that have the discipline to edit their work.  Generating gameplay ideas is exciting and easy; discerning those with potential and removing the rest takes resolve and vision.  But you’ll never get where you are going if you walk down every road — you must cut!

Removing game elements is usually straightforward.  They are almost always part of a collection of similar elements, so they can be compared on an apples-to-apples basis.  They are often specific instances of a general system — the Assault Rifle is an instance of the Weapon system, the Goblin is an instance of the enemy AI systems — which means that most of the work that goes into them can be applied to other elements and isn’t wasted.  An element is associated with a certain amount of work that must be scheduled for the models, textures, effects, sounds and animations, so it is easy to measure its impact on the overall scope.  And finally, since an element is by definition discrete, it can usually be removed with virtually no impact on the rest of the game.

This guy's name is Needler

Some elements just don't fit in

“Is this mechanic going to be fun?” is a good question, but impossible to answer.  Prototyping can help, but it still takes discernment to recognize the potential in a prototype.  It also represents an investment of resources, which can bias the team toward keeping a prototyped mechanic that ought to be cut.  “Can we implement this mechanic?” is also a good question, but “can” is not “should” and “implemented” is not “tuned”.  “Has a mechanic appeared in another game?” is a useful question, but isn’t necessarily relevant to the current game.  “Does everyone agree this mechanic is good?” is a seductive, but destructive, question; it replaces a designer’s instinct with general consensus and will lead to “downhill design” where the only possible solutions are the easiest ones.  The single best question for determining the potential of a mechanic is “Can the player be taught to enjoy this mechanic?”

He's about to have an experience he won't forget!

Not everything is teachable

Answered honestly, this question has far-reaching implications.  If a player never uses a mechanic, it might as well not exist in the first place.  If a player fails to realize that a mechanic exists, it is too subtle or the game is overly complicated.  If a player refuses to learn a mechanic, it probably doesn’t fulfill a fundamental aspiration for them — they will never be interested.  If a player is unable to learn a mechanic, it is probably unintuitive or it clashes with other aspects of the game.  If the designer cannot distill a mechanic down to teach it, they likely don’t understand the mechanic themselves.  If a mechanic can only be learned through explicit tutorial, it probably has an awkward or obscure control scheme.  Any of these problems are fundamental enough to warrant removal.

On the other hand, if a mechanic can be taught effortlessly — or better yet, players discover it on their own — or if mere awareness that an experience is possible is enough to motivate them to learn how to access it, this is a sign that a mechanic is reaching them on a subconscious level.  This kind of mechanic can be integrated into their thought process and lead to a fluid flow experience.

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Definition: Role

Role

The features, mechanics, situation and purpose which define an element’s function in a game

According to Aristotle, we can claim to have knowledge of something only when we have understood its causes.  These causes come in four types: the material cause – the matter of which the thing is made, the formal cause – the pattern or idea which that matter takes, the efficient cause – the motivation which formed the matter, and the final cause – the purpose for which it is used.  Once we understand all four causes, we know an object fully.  In game design terms, once we can explain all four causes, we know an element’s role.

The Material Cause

Video games are not physical objects, so technically they don’t require a material cause.  However, they do have underlying components that make their existence in the game possible, like models, textures, effects and sounds.  They also require other engine features like physics, particles, etc.  Some elements even require completely unique features, and explicitly specifying these features is important to defining the role.

The Formal Cause

This aspect of a game element is what we traditionally think of as “design.”  The form of an element is the pattern that it follows and the systems in which it operates – the game mechanics that constrain it.  Aristotle is referring to the Platonic idea of an object, but in-game design this is the Paper Design.  Just as in Plato’s theory, real life cannot match the perfection of the world of ideas; the in-game experience will never realize the paper design exactly, but it does provide an objective standard.  Much like a craftsman making a chair is attempting to create a material version of the ultimate idea of “chairhood”, the designer tunes an experience to get as close as possible to the original game design.

The Efficient Cause

Often called the “moving cause” because it provides the motivating force for an object, the efficient cause is closest to our modern concept of “cause and effect.”  In game design, the efficient cause is always the player and their desires.  A game element that does not have a corresponding player desire will never be used (at least not without coercion) so it is crucial to identify and meet those needs.

The Final Cause

The most important cause, at least to Aristotle, is the purpose for which an object exists.  In a game, this is especially true because games are fundamentally about using tools to solve problems, and game elements are usually classified by the types of problems they solve.  This is why it is so important to limit an element’s power so it is only effective for its designated role; if an element is an effective solution for multiple types of problem it becomes difficult to tell what its purpose is intended to be.  This is also why a problem should be presented before or at the same time as the solution, or else the player will not have a way to categorize the solving element.  This purpose is communicated to the player through affordance and reinforced by rewarding feedback.

Taken together, these four causes define an element’s role.  The features that allow it to exist.  The mechanics that give it a form and constrain its use.  The situation that creates the player’s need for it.  The purpose for which the player will use it.  Once a designer understands all four causes for an element, they understand an element well enough to implement it successfully.

GDC 2010: Design in Detail XIV


If you were disciplined in writing your paper design, and stayed firm while doing setting up the rough balance, this stage should be very rewarding and exciting.  If not, it is going to be disappointing and frustrating.


The timing for this stage is tricky.  If you start too early, your balance changes will be swallowed up by the churn of new features coming online.  If you wait too long, the rough balance will become entrenched and the team will object to changes.  Generally, this coincides with a “First Playable” build where everything is at least in the game and functioning.

It’s crucially important to communicate this new phase to the rest of the team, so they know what to expect and understand that now is the time for them to give the feedback they have been patiently waiting to deliver. One way to do that is to implement a controlled opportunity for them to play the latest build and provide their feedback in a structured format.  Make sure you tell them what you are currently working on, so their responses will be relevant, but don’t tell them exactly what has changed or you may bias their opinions.


So how do you balance a Sniper Rifle? It is not by adding weaknesses!  Don’t undo the work you did in making it powerful!  Balance it by narrowing its role through limitations.


The best way to detect which elements need to be limited is by watching for the game to become predictable.  If the same strategy is being used in a variety of different situations, to the point where players are no longer required to think about which strategy to choose, it means an element is too useful outside of its designated role.  If the Sniper Rifle is not only the best weapon at long range, but players are carrying it indoors and using it against vehicles, it needs to be constrained.  Give it some time first, because the playtesters might just not have figured out the new balance yet, but if it is consistent for a few tests, start looking for ways to limit the dominant element.

On the other hand, if the game is completely unpredictable, it is a sign that the elements are not effective enough at their roles.  A truly random strategy should never be as good as intentionally selecting an element that is strong in the desired role.  It may also be a symptom of a role going unfulfilled.  If there is no Sniper Rifle, the Shotgun and the SMG are equally terrible at long range combat, so it doesn’t matter which one you choose.

Balance of Power II

Tank Beats Everything

Even in the case where an element cannot be limited by role, it can be limited by availability.  Sometimes the Player should feel overpowered, either as a reward for a good player or as a temporary boost for an average player.  A game that is nothing but a relentless competence test can become monotonous, especially once a player has reached the limits of their physical ability to get better.  Giving them an occassional taste of unmitigated power relieves the pressure to perform and is an excellent palate cleanser.  An element that is fun and fulfills a player aspiration but can’t be limited to a single role is an excellent candidate for this experience.

No mana?  No problem!

Take that, Rock, Paper and Scissors

A successful transition from “balanced” to “overpowered” usually requires some changes, though.  It needs to be exaggerated so the sounds, effects, even the fiction, match the new power level.  It should become a featured element on a single level or two, the player should feel special for getting to use it, and the enemy resistance should be ratched up as well to highlight how strong they have become.  The element should also be made as modal as possible, so the player knows when the “overpowered” experience begins and it is clear when it is supposed to end and resume normal gameplay.

In a Corner

Let’s say an overpowered element doesn’t fit in any of these categories.  It isn’t just a perceived imbalance, the other elements can’t be strengthened to an equivalent power level, the role can’t be limited or enforced, and it isn’t appropriate for an over-the-top set piece.  If nothing else can be done, it has to be weakened somehow, right?  Let me tell you about The Needler

The Needler is a weapon from the Halo series.  It fires a stream of neon pink projectiles that actively track enemy targets.  On impact, each needle embeds itself into armor or flesh, remaining there for a few seconds before detonating and causing further damage.  If a character ever has more than 5-6 needles attached at any given time, they all explode in a particularly lethal chain-reaction known as the “Pink Mist”.  It first appeared in Halo 1 and was the bane of my existence for 10+ years because it was incredibly fun to use, but equally impossible to balance.

Like this, only a couple feet lower

I feel a headache coming on

It would start out too powerful, so we would weaken it.  Which would make it useless, so we would change the mechanics.  Which would make it effective in too many situations, so we would limit its placement.  We ended up drastically weakening it right before we shipped to prevent it from wrecking the game.  Three times!  The amount of effort, thought, debate, programming and art resources, playtesting surveys, data analysis and sleepless nights that were poured into the Needler far outpace any four other weapons combined.

So, even if an element cannot be balanced in any other way, the answer is still not to weaken it, but to cut it completely.  It is too difficult to weaken an element without destroying what made it fun in the first place, and the end results won’t be worth the hassle.  It’s best to just save it for another game where it will fit without compromise.

Balance of Power

“Iron sharpens iron, and one man sharpens another”

-Proverbs 27:17  [ESV]

“The whats-it is too powerful.”  It could be a weapon, an RTS unit, a character in a fighting game, a multiplayer class… it doesn’t matter because all chronic balance problems follow the same general pattern.  The game starts to revolve around a single dominant element, which is inherently overpowered and reduces the game’s strategic complexity, ultimately limiting its longevity.  Nobody notices when a single element is too weak, because they just avoid it.  And nobody complains when a dominant element increases strategic complexity, because that makes the game better and more fun.  And a simple problem, like a damage value that is just set too high, usually has a simple solution that is quickly applied.  But for chronic, fundamental balance problems, the designer is repeatedly faced with the same decision.  Should the dominant element be weakened for the sake of balance?  (Hint:  The correct answer is always “NO!”)

Perception is Reality

First, it is important to recognize that the only “balance” that matters is the balance that players perceive.  The goal of balance is longevity, and if players continue to play because they believe the game is fair, it doesn’t matter if it is objectively balanced in some measurable sense.  In fact, if a large enough community perceives the game to be balanced, but your metrics claim it isn’t, then the metrics are wrong.

Nice Gear

Sometimes power is deceptive

So often the problem isn’t that an element is too powerful, but that it feels too powerful.  Maybe its a gun with a really great firing sound.  Or a new unit that players haven’t figured out how to counter yet.  Or perhaps it appeals more to skilled players or everyone is using it because it is new and novel.  These problems usually fix themselves if they are left alone.  I changed the perception of an “overpowered” weapon during Halo’s development just by announcing that I had fixed it (even though I hadn’t actually changed anything.)

The Tooth Fairy is Overpowered

In almost every case, there is no such thing as an “overpowered” element; there are well-tuned elements in a crowd of underpowered, ill-tuned alternatives.  The Sniper class is implemented and all of the sudden you can’t take three steps without being headshot from across the map.  The problem is not that the Sniper is strong, but that the Medic and the Engineer are weak.  It’s easier to make a potent Sniper, so it immediately outclasses the rest.  Instead of spending time figuring out how to cripple the Sniper, focus on making the other classes equally awesome.  Or better yet, ditch the ones that will never feel as powerful as the Sniper and choose different classes that have their own natural strengths.

Get it?  Because neither one exists!

His only weakness is his terrible agent

 

Too Powerful, or All-Powerful?

In the paper design balance pass, every element should have been given a role to fill.  Sometimes an element breaks the balance by breaking its designated role.  An anti-vehicle missile that can be used against a crowd of infantry.  A “glass cannon” that can hold his own in a melee fight.  A long-distance weapon that is just as effective at point-blank range.  The solution in this case is not to weaken the element, but to restrict it so that its strength cannot be applied in as many situations.

Often it takes ingenuity to limit a weapon without weakening it, but it isn’t as difficult as it might seem initially.  A global weakness will affect the player in every situation, so a heavy-handed global weakness will be a constant irritation.  But a specific limitation will only be felt when an element is being used outside its role, which a player can learn to avoid, eliminating the annoyance entirely.  Nobody complains that their fancy sports car doesn’t work underwater, they just stay on the bridge.

[Continued in Balance of Power II]

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.

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.

Pac-Line

(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?