Glossary

These definitions are intended to be relatively brief and opinionated. They are not authoritative!

Game Design

Key concepts and terms from game design.

Accessibility

How easy and/or comfortable a game is to play for players with a wide range of ability levels or impairments.

Vision, hearing and motor disabilties are the most common category here, but difficulty, time commitments and mental health concerns can also be reasonably considered under a broad banner of accessibility.

Achievements

Rewarded for accomplishing challenging or interesting in-game tasks. These are often associated with achievement points, awarded based on the difficulty of each achievement.

Can serve as an important form of tutorialization, as it lays out [goals] for players to chase after (and are a good spot for hints).

Achievements typically tie into out-of-game systems on Steam or consoles to track accumulated achievements.

Agency

The extent to which players feel like they can shape the broader narrative or mechanics of the game.

Art style

The techniques, colors, scale and elements that are used in the visual elements of a game.

Automation

Repetitive work that is done automatically by in-game entities and systems.

Challenge

Difficulty that is fun and rewarding for players to overcome.

Cohesion

The degree to which game elements (usually thematic or artistic) feel like they belong together as part of a greater whole.

Constraint

A limitation of the design space, which must (or should) be respected when doing game design.

Constraints can be:

External: imposed by problems beyond the game designer's control. Budget, cultural sensitivity and market demands are common examples.
Arbitrary: imposed by the designers themselves, in order to limit the design space in interesting ways.
Internal: implied via existing elements of the game, or the combination of other constraints.

While constraints are limiting, they're a powerful tool to create a more focused game and are great sparks for creativity.

Constraints exist on a continuum between soft (flexible, can be ignored with a good enough reason) and hard (must be respected at all times).

Constraints can be in tension with each other.

Cycle (mechanics design)

A set of elements of the same type that share strong mechanical (and often thematic) similarities.

Design-by-stumble

Making games is hard! Starting with an existing, successful game is a popular and effective strategy.

However, you should critically examine the genre of the game you are starting from, and identify clear areas to focus on and improve.

Otherwise, your game development process will proceed as if by random walk: changes made without a reason are as likely to be harmful as helpful, and your game will be unfocused.

Design space

The set of all possible games or solutions that obey all of the constraints.

Depth and complexity

Depth is a fuzzy term that gets at the notion of game richness: how many interesting choices are there, how much replay value exists?

Complexity is a similarly fuzzy term that attempts to capture a measure of the number of "moving parts" of a game, and how challenging it is to understand.

Depth is generally viewed as a positive attribute, while complexity is generally viewed as a negative attribute. Games which have high depth relative to their complexity are often considered elegant.

Dependending on their player base, games have a varying complexity budget. This fuzzy term represents each player's ability to keep track of rules, learn new mechanics and reason effectively about their choices. If this budget is exceeded, players will be frustrated and confused by your game.

Diagetic

A mechanic that is presented as occurring in the literal game world. For example, most user interfaces are presented as something that only exists for the player's convenience, but doesn't exist in the game. However, in Halo, the display is part of the soldier's visor, and thus literally exists in the game.

Antonym: non-diagetic

Double-edged

An upgrade or other mechanic that has both benefits and drawbacks. These are typically stronger than their strictly positive equivalents in order to be balanced.

Early game, mid game and late game

These are broad stages of a game, which proceed one after another.

Total complexity typically increases as the game unfolds, as the complexity budget is often limited by the rate at which players can learn and master new mechanics.

Focus (game design)

A game is said to be focused if it has a clear goal and its systems are built to serve that goal.

Flavor text

Writing (or sometimes other elements by analogy) that has no mechanical impact or explanation, and instead serves to enhance the theme and tone of the game.

Game feel

How satisfying, smooth, intuitive and natural a game feels to play. Games with great game feel start to feel like extensions of the player's body as they master the game.

Genre

A cluster of related games. These can be explained either by definition (where you list key properties of games in the genre) or by example (where you list games that fall into the genre and those that do not).

Hook (game marketing)

The unique selling point of a game, that draws interest and encourages players to try out and keep playing your game instead of the competitors in your genre.

Hook (game systems)

A reusable game mechanic that can be used to connect game systems, increasing cohesion and depth.

Interesting choices

Games are sometimes said to be a "series of interesting choices". In order for choices to be interesting, players must be able to:

Understand the choices they have
Understand the implication of each choice
Care about the impact that the choice has on the game
Decide differently based on game conditions

Choices are said to be balanced if they provide roughly equivalent benefits (or drawbacks) to the players.

Lens (game analysis)

A perspective on the design of a game. See the deck of lenses for an excellent set of questions to ask about your games.

Loop

A path through a game system that leads back to itself.

Each step in a loop can be reinforcing (positive feedback) or dampening (negative feedback), resulting in an overall reinforcing or dampening cycle.

Ludotography

The telling of a story through gameplay. From this video.

Mechanic

A rule about how the game works.

Narrative

The story of a game. Unlike most traditional works of art, narratives are often implicit or branching in games.

Noob-trap

Features that seem helpful or appealing to beginners, but actually aren't.

Using them is less effective in almost every circumstance than an alternative, or develops bad habits.

Plausibility and realism

Fictional worlds are plausible if they have a set of learnable, internally consistent rules. They are realistic to the extent to which these rules match those of real life.

Worlds that lack plausibility will not be immersive, and will not feel coherent.

Player avatar

The in-game unit that represents the player.

Player experience

What the player is actually doing, and how they feel.

Player goals

In-game objectives that players set for themselves that give them a reason to keep playing. These are often complementary to player fun: fun will keep players engaged and enjoying themselves from moment to moment, but chasing after and reaching goals gives a deeper satisfaction and sense of mastery.

Polish

Work done to improve how pretty, cohesive, and bug-free a game is. Games where these qualities are high are said to be polished.

Progression

The increase in player power and options over time. Progression exists on a continuum between vertical, which is focused on power growth, and horizontal, which is focused on expanded options.

Prototype

A quick implementation of a game design idea used to test a hypothesis about how a mechanic will work or feel in practice.

Quality of life

Features which improve game feel and reduce player frustration. This is often done by reducing the amount of manual repetitive work, alleviating limitations like storage space, or reducing the ongoing complexity budget required by game mechanics.

Randomness

There are two kinds of randomness: input randomness and output randomness.

Input randomness controls which options a player is presented with, while output randomness varies the effect of a player's choice. Both add challenge and surprise, but input randomness is typically less frustrating.

See this GMTK video for more.

Simulationism

A style of game design that attempts to accurately simulate real-world systems in an realistic fashion.

System (game design)

A collection of mechanics that work together to produce part of the player experience. Systems generally have loops back to themself, or hook into other systems in order to keep the player engaged and create depth.

Tension

Elements of the game design that are, at least on their face, contrasting or opposed. Tension must be handled carefully: tackled poorly, it leads to poor cohesion or focus. Tackled with thought and skill, tension can creating unique and interesting themes, tone or systems.

Theme

The setting, aesthetics and "fictional genre" of a game. This is the core of worldbuilding, and sets the basic rules of the fictional universe.

Can be described using:

very broad terms like "sci-fi"
more specific like "colonial fantasy focused on the war between burgeoning powers"
hearken to specific media like "Diablo" or "Bladerunner"

This can be extended to discuss the big questions that a game is attempting to explore, like "what does it mean to be human".

Tone

The emotional weight and mood of a game. Often discussed in concert with a game's [theme]: "cheerful steampunk" is very different than "horrific steampunk" is very different than "gloomy steampunk".

Tuning levers

Parts of a mechanic that can be easily tweaked to modify the balance of a system.

Tutorialization

The practice of teaching new players how to play your game.

Upgrade

An improvement to a mechanic. Upgrades are usually but not always selected by players to give them a sense of agency.

Worldbuilding

The lore, places, people, aesthetics and internally consistent rules of your fictional universe.

World generation

Usually refers to the procedural generation of a game world, or parts of a game world, in opposition to the crafting of a world (or level) by hand.

Closely related to concepts of:

randomness: a pristine world provides a particular set of options for a player to begin engaging with, and these options should allow the player to meaningfully engage given the mechanics available to them
plausibility/realism: a procedurally generated world must make sense given the game's world building

Factory Builders

Terms defined here are standard elements of the factory builder genre.

Alert

A notification that lets the player know when something has gone wrong.

Assembler

A building or machine that can be used to process items via a recipe.

Balancer

Joins two or more item streams and evenly distributes items across them.

Commonly combined with balancers or built out of splitters.

Belt

A belt is a simple logistic entity which transports goods in a single direction. Multiple belts need to be chained together to provide effective transportation. Belts usually have a maximum amount of goods they can transport per unit of time. They can transport any type of solid goods and different goods can be mixed.

Notably, in Factorio, belts have two "sides", where each side can contain different types of items. The direction from which items are loaded onto the belts influence which side of the belt the items are put on.

Examples:

Bot

Bots are units which can automate specific player actions. They often require a lot more upfront investments than machines, but are a lot more flexible. Compared to machines, bots can move around freely. Some actions can only be automated through bots, e.g. constructing new entities.

Examples:

Blueprint

Blueprints are placeholders for multiple entities to be constructed. Entity settings (e.g. recipes or other configurations) are preserved in the blueprint. They can serve as a planning tool for the player, but also be used as instructions for bots. Often, blueprints can be shared between players and/or be reused during the game.

Examples:

Clipboard

Similar to blueprints, the clipboard allows the quick reuse of factory layouts. A set of entities can be marked to be copied and then pasted at a different position at a later time. Usually, the entities are not built directly, but only pasted as placeholders.

In contrast to blueprints, players can usually only have one layout in the clipboard. Previously copied layouts are simply overwritten.

Examples:

Factorio: Controls/Tools (copy/paste/cut)
Dyson Sphere Program: Mass Construction (Lv1) (enables copy/paste functionality)

Creative mode

A game mode where the player can freely test out designs and modify the environment in unconstrained ways.

Often incorporated into the game itself as a "sandbox" or "lab", not to be confused with the other genre-specific meaning of either of those terms.

Encyclopedia

A list of in-game elements (items, locations, mechanics) that explains what they are and key properties.

Intended as an in-game substitute for a wiki. Often contains flavor text, and serves as a primary mechanism to explain worldbuilding to players in this genre.

Filter

Filters allow only one set of goods to pass through. Can be combined with inserters to only transfer one set of goods or with splitters to split one set of goods to one side and all other goods to the other side.

Examples:

Factorio: Filter inserter
Factorio: Splitter (provides filter functionality)
Satisfactory: Smart splitter (provides filter functionality)
Dyson Sphere Program: Sorter (provides filter functionality)

Inserter

Inserters transfer goods from one entity to another. Often, inserters are required to insert goods into machines. Inserters are usually available with different ranges, either as separate entities or as configuration option.

Factorio: Inserters
Dyson Sphere Program: Sorter (provides inserter functionality)

Lab

A machine to research new technologies, unlocking new machines and other gameplay features. Usually uses science packs as input.

Loader

An entity that can load or unload the contents of a container as fast as the input/output belt can handle. In many games (like Mindustry), this is built into assemblers directly and inserters simply don't exist.

Factorio, where it was initially considered but ultimately not included

Logistic network

A network of connected logistic elements that can interact with each other. It's composed of:

producers, who provide resources to the network
consumers, who take resources out of the network and use them
the connection between these nodes

A single entity might be both a producer and a consumer. In the same game there may be different separated sets of logistic networks. The consumers in the network (e.g. logistic bots) can access the producers in the network (e.g. logistic chests), but not outside of it.

Examples:

Factorio: Logistic network

Map

An abstract representation of the geography of the game world. Typically stylized, and intended to communicate large amounts of information comfortably.

Unexplored areas are covered in fog of war, concealing them.

Notes

Player-written in-game notes. Often integrated with the map. Typically used for:

marking important locations
recording what to do next
ideas for potential improvements
explanations of why weird decisions were made

Serves as a combination of programming comments, map annotations and project management tools.

Overlay

Overlays are UI elements which allow the player to view additional information about entities or processes. They help convey information that is not easily visible by the in-game graphics alone. The player can switch between different overlays to access different types of information or disable them entirely.

Examples:

Factorio: "Alt mode"
Oxygen Not Included: Overlays

Pipette

The pipette is a tool to select an entity and/or its configuration directly from the screen. It works similarly to copy/paste functionality with the clipboard, but for a singular entity. This is usually a UI tool instead of a physical tool to build in the game.

Power

Power is a special type of resource that is required for machines to run. Power needs to be produced and then distributed to the machines. Often, there are different means of production (e.g. steam power, solar power, nuclear power) with different upfront costs and production rates. The distribution of power is usually separated from the distribution of other resources (e.g. through an electric network).

Production statistics

Records how much of each resource you're producing and consuming. Advanced versions have sophisticated filting

Works well in a dashboard format.

Prioritizer

Joins two or more streams of inputs, causing the input or output to take priority:

input priority: if output flow is greater than input flow, take from the stream with priority
output priority: if input flow is greater than output flow, send goods to the stream with priority

Commonly combined with balancers.

Recipe

How items can be combined to make new items. Contains:

input(s), including quantities
output(s), including quantities
processing time
what assemblers can be used to make it

Recipe

Research

Research is the main means of progression. Researching new technologies unlocks more machines, enables more advanced processes or improves existing features. Research is usually very expensive to pace the game.

Examples:

Resource

An item that can be processed further to produce different items.

There are different types of resources:

Raw resource: A foundational resource that can be extracted directly from the environment.
Intermediate resource: A resource that cannot be extracted nor used directly. It's an intermediate set towards the production of end products.
End product: A resource that can be used directly for some in-game benefit.

Sandbox

Science pack

An intermediate resource that can be used to research technologies in a lab. Often, many science packs are required to unlock one technology. Sometimes, science packs are available in different types with different recipes, different technologies require different science pack types to be unlocked.

Examples:

Splitter

Splits streams of goods into two.

Train

An entity to efficiently move big amounts of resources over large distances. Usually require a much higher upfront investment than belts, but are better suited for long distances. They are high latency, and move goods in clumped bursts. In some games there are also many other entities to guide the behavior of large train networks.

Examples:

Undo

Reverse previous directions or actions. Ideally combined with a redo functionality.

If buildings exist / don't exist when they need to, marks structures for deletion, or creates ghosts in their place.

Ecology

These terms come from the science of ecology and its related fields.

Nutrient cycle

The recycling flow of nutrients between organisms, decaying matter and inorganic stores.

Soil

Dirt, but viewed scientifically. Useful for growing stuff.

Soil has four main components, which vary in water storage capacity and drainage.

Sand: large particles. Drains well, but water storage capacity suffers.
Silt: medium particles. Pretty balanced.
Clay: small particles. Drains terrible, but with great water storage capacity.
Organic matter: used to be living stuff, carefully prepared and mixed in the soil. Great drainage and water storage, but decomposes.

Water cycle

The recycling flow of water: from rain to lakes and rivers and soil to plants and animals to eventual evaporation.

Water storage capacity

How much water remains in soil after being flooded and drained. Too low and your plants will be susceptible to drought.

Water drainage

How quickly water can drain out of soil. Too low and your plants will be susceptible to flooding.

Emergence

These terms are specific to the game design of Emergence. Even if they have an external meaning, when used in this book, they will reflect this meaning.

Assimiliation

Capturing and domesticating a species, giving you access to it as part of your colony.

Building

An inorganic structure that is not alive.

Life cycle

The collection of life stages of an organism, and the pathways between them.

Life stage

A form in an organism's life cycle. This controls its appearance, capacities, needs, and which life cycles it can transition to.

These are modelled in discrete steps to improve clarity and reduce complexity for players.

Milestone

Per-playthrough accomplishments. Contrast to achievements, which are unlocked a single time for each player.

Organism

A living creature (plant, animal, fungal or otherwise) with life cycle. Organisms can be split into units, which move, and sessile organisms which do not.

Signal

Every physical object in the game emits signals that correspond to their identity. These spread over time, and are used for pathfinding and work prioritization. There are three flavors of signal:

presence
supplying (a "push" signal)
requesting (a "pull" signal)

Depending on their needs and preferences, units will proactively pick up items from buildings that are supplying items, and move them to buildings that are requesting items of that type (or simply storing those items). Alternatively, units will proactively carry items away from buildings that are supplying them.

As a result, signals serve as both a pathfinding tool and a logistic network to transport goods through the factory.

Game Design for Emergence