C HAPTER 10 CORE MECHANICS ZHONGSHI XI RACHEL MAILACH CORE - - PDF document

CORE MECHANICS:

• determine how the game actually operates
• heart of the game
• defines rules and game-play

CHAPTER 10

CORE MECHANICS

ZHONGSHI XI RACHEL MAILACH

ANSWER:

• B, because…

A does not specify details of the time, i.e. how long the delay is before the row is eliminated, or how this will affect any other rows, A is a RULE, not Core Mechanic C does not specify what “stick” means and what type of collision it is (ie, collision on the sides does not make it stick), also speed at which shape falls is not specified D does not explain what “outside the boundary” means

Quiz 1

What are the core mechanics of Tetris?

A. A row is eliminated if and only if it is completely filled with blocks. B. The player hits the left arrow key to rotate the current shape counter-clockwise by 90 degrees immediately and permanently. C. The shape will “stick” at the position when one of its blocks collides with other blocks

• therwise it will continue to fall.

D. The game is over when there is a block outside the boundary.

Tetris 1.68

• It is your job as the designer to convert general

concepts into detailed rules.

• These rules will later be turned into algorithms. The

more specific the rules, the easier they are to convert to algorithms. EXAMPLE:

• “Early stages of game design”
• not well defined: What is the penalty? How

long does the player have?

• “Core mechanics stage”
• defined like algorithm
• uses words like when, and if
• views game as state machine

DESIGN RULE: Design the game, not software (let the programmer handle the code implementation)

Turning Rules into Core Mechanics

Early stages of game design: “Players will be penalized for taking too long to get through the swamp.” Core mechanics stage: “When the avatar enters the swamp, the black toadstools begin to emit a poison gas that the player can see filling the screen, starting at the bottom and rising at a rate of 1 game-world inch every 3 seconds; by the end of 3 minutes, the gas reaches the height of the avatar’s face, and if by that time the avatar is still in the swamp, the avatar dies. If the avatar returns to the swamp later, the gas is gone but the process starts over again from the beginning.”

• Operate internal economy of the game – how game

creates, distributes and uses up goods on which game bases its economy.

• Presents active challenges to player via UI as the level

design specifies.

• Player actions – converts actions from the UI and

implements into game world.

• Detects victory or loss – controls termination conditions,

applies whatever consequences rules call for.

• Operates AI of non-player characters and opponents.
• Switches states of game – keeps track of current game-

play mode and when a mode change is needed, the core mechanics switch the modes and signal the UI to update accordingly.

• Transmits triggers to storytelling engine – when game

events or player actions call for plot to occur.

What the Core Mechanics Do

Age of Empires

REAL-TIME

• core mechanics specify parameters of a world that operates on

its own whether the player acts or not

• processes operate continuously
• wait for event triggers

TURN-BASED

• core mechanics don't do anything until player takes turn, then

effects are computed

• in some games, all players enter actions simultaneously, then

core mechanics compute effect of all players' actions

• design will read like sequence of events -each possible action

has effects

• if game has artificial opponents, mechanics do not remain

entirely idle between turns, because they must compute behaviour of the opponents, though the opponents still act in turns

Real-time vs Turn-based

Civilization Warcraft II

LEVEL DESIGN

• Level design specifies: type, timing, sequence of

challenges

• Core mechanics specify how challenges work but

not which challenges the level contains

• read level design data from file
• initial state
• challenges
• actions
• NPCs (Non-Player Characters)
• victory conditions

Core Mechanics and Level Design

RESOURCES

• objects or materials in the game that can move or be

exchanged (handled in numeric quantities)

• a resource represents a type of object
• the core mechanics define processes by which the game

creates, uses, trades and destroys resources

• may be of a type that can be handled individually, such

as marbles, or it can be of a type not individually handled such as water

• games treat non-measurable concepts such as popularity
• r resistance to poison as resources although in reality

they can not be used as quantities that can be measured and be bought and sold.

Resources

Star Craft

RESOURCES EXAMPLE: Wood constitutes as a resource in your game if your player can pick it up, trade it, and put it down again. BUT the resource doesn’t describe a specific marble in your player’s pocket. Wood is a resource, but the 3 wood cards in the player’s hand are an instance of the resource, referring to a particular collection of that type, in this case, wood. Thus the cards in the player’s hand are entities.

Resources

Settlers of Catan

ENTITIES

• a particular instance of a resource or a state of an

element in the game world (eg. Light, on/off)

• a resource is a type of thing, but an entity is the thing

itself

• a building, character, animal, pile of gold, or vessel of

water can be an entity.

Entities

Diablo 2

SIMPLE ENTITIES

• single value stored data can be numeric such as a score,
• r symbolic like the state of a light
• eg. State of traffic light – initial state, and a list of all its

possible states is stored

• eg. numeric entity – initial quantity, and range of

possible legal values is stored

Simple Entities

COMPOUND ENTITIES

• takes more than one data value to describe eg. Vectors

such as wind which has 2 attributes, speed, and direction

• each attribute acts as a simple entity, OR a compound

entity Example: objects in OOP

• variables for storing numeric and symbolic values
• may be made up of other objects (same way entities can

be made up of entities)

• classes of objects contain functions or methods (entities

have associated mechanics) for data manipulation

• This is why entities are almost always implemented as
• bjects in code

Compound Entities

ANSWER:

• A. Entity/Resource
• B. Entity
• C. Entity/Resource
• D. Entity/Resource
• E. Neither

Quiz 2

Which of the following are entities, and which are resources?

• A. Money in Command and Conquer
• B. Number of Mario’s lives in Super Mario
• C. Guns in Counter-Strike
• D. Crystals in Starcraft
• E. Sky in Sonic the Hedgehog

UNIQUE ENTITIES

• If game contains only one entity of a particular type (eg.

the avatar b/c there is only one)

• EXAMPLE: In a football game, the football is a unique

entity, because there may never be two footballs in play at any one time

Unique Entities

FIFA

ANSWER:

• No, if there are multiple avatars it is clearly not

unique

Quiz 3

Two players play Street Fighter on the same machine. Player A picks Ryu in white and Player B picks Ryu in blue. Is Ryu a unique entity in Street Fighter?

Street Fighter

MECHANICS

• documents how the game world and everything in it

behaves

• states the conditions that trigger events and processes
• describes the overall rules of the game, operates

throughout the game, global mechanic

• any game with more than one game-play mode

needs at least one global mechanic to control when to switch modes

• describes behaviour of specific entities from basics (eg. a

light switch) to complex entities (eg. an AI)

• recall list from section Functions of the Core

Mechanics in Operation

Mechanics

Hearthstone

NUMERIC RELATIONSHIPS

• relationship between entities defined in terms of numbers and

arithmetic operations

• You must ensure that your equations are meaningful and will

not have errors (eg. divide-by-zero) EXAMPLES:

• bird’s initial velocity
• energy stored in the stretched rubber band

SYMBOLIC RELATIONSHIPS

• values of symbolic entities (eg. red, on, off), cannot be

manipulated algebraically

• a two-state entity is called a flag

EXAMPLES:

• state of pig’s life (alive OR dead)
• state of pig being hit (hit OR not hit)

Numeric & Symbolic Relationships

Explore the two relationships in the game Angry Birds with respect to core mechanics.

Angry Birds 1

• Event is a specific change that happens after being triggered by a

condition, DO NOT occur continuously, it doesn’t happen again until triggered again

• Process is a sequence of activities that once initiated, continues until

something stops it

• Conditions is what causes a process to start or stop
• If (condition) then execute (event)
• Or if (condition) then do not execute (event)

EXAMPLE:

• Events:

1. Ghoul is hostile towards player 2. Ghoul is not hostile towards player

• Processes:

1. Ghoul wanders around area 2. Ghoul stops wandering 3. Ghoul approaches player 4. Ghoul attacks player 5. Ghoul stops attacking player 6. Ghoul returns to original position

Event, Processes & Conditions

Example: World of Warcraft. A ghoul is wandering around in an area of 500m2 at 1m/s. If the player comes within 10m of the ghoul, it will stop wandering, and approach the player at 3m/s. When the ghoul reaches less than or equal to 1m distance from player, the ghoul will start to deal damage to the player at a rate of 5 health points per second. Until the player leaves the wandering area of the ghoul (500m2), the ghoul will fight him until death. If the player runs outside the wandering area

• f the ghoul (500m2), the ghoul will stop

attacking the player and return to the position it was at before approaching the player and continue wandering as it was.

Event, Processes & Conditions

Grand Theft Auto IV

• Economy - system in which resources and entities are

produced, consumed and exchanged in quantifiable amounts

• Example: Risk - economy is quantified by armies!
• Example: Battle Games - enemies are part of the

economy, a resource, consumed by fighting with avatar

Internal Economy

Risk

Sources

Monopoly

SOURCES

• if resource or entity can enter the game world having not

been there before, mechanic is called source

• part of the economy as it pays the player a type of

interest at regular intervals on the resource he owns

• spawn point - designated location where core mechanics

insert new resources

• when designing your source, you must define a

production rate

• production rate - either fixed or variable (eg. max

amount of ammo, stops producing when it gets full)

• sources can be limited or unlimited (eg. in Monopoly,

the “Go” square is an unlimited source)

Quiz 4

Which of the following is a source?

• A. League of Legends, Crystal, minions spawn points
• B. Civilization V, gold mines
• C. After accepting a mission in EVE, a quest item is then

placed into the player’s ship

• D. Borderlands, enemies drop items

League of Legends

ANSWER:

• A,C and D are all mechanics by which resources or

entities enter the game world when not having been in the game world before

• B is an entity

Drains

Call of Duty: Black Ops 2

DRAINS

• drain - mechanic that determines consumption of

resources, time before it disappears

• Players don’t mind getting money for free, but when

they have to spend it, they want to know why. Explain your drains! EXAMPLE: Weapon drains ammo decay mechanics

Convertors

Minecraft

CONVERTERS

• a mechanic that turns one or more resources into another

type of resource

• specify the production rate and the input-to-output ratio

Example: Minecraft Crafting Table

Traders

Skyrim

TRADER

• mechanic that governs trades of goods, generally

between the player and the game

• traders cause no change in game world other than

reassignment of ownership Problem of runaway profits: A player must never be able to repeatedly buy an item from a trader at a low price and sell it back at a higher price.

You must set the limits, by:

• 1. making it impossible to make a profit (all subsequent

sales to be less than purchase price)

• 2. make a reasonable profit (limit amount of buying and

selling they can do, eg. put time limit)

• 3. limit trader’s funds
• 4. in multi-player game, allow players to only buy and sell

from one another

Quiz 5

Which of the following are drains, converters or traders?

• A. Monopoly, when player passes “GO”, player receives

$200

• B. Super Mario, star grants Mario short time of invincibility
• C. Assasin’s Creed, player makes 1 smoke bomb from 2

units of smoke powder, and 1 metal shell

• D. Crysis, after cloak ability is engaged, the power of

nano-armor starts to go down at a rate of 2% per second

ANSWERS:

• A. Is NOT a drain, converter or trader, it is a

source

• B. Is NOT a drain, converter or trader, it is just a

simple mechanic. It is arguable that it is a converter iff the star and invincibility time are considered a resources. (i.e. Star -> 30s invincibility time)

• C. Converter
• D. Drain

Quiz 6

Which of the following are drains, converters or traders?

• A. World of Warcraft, after player sells a

sword to a merchant for 100 gold

• coins. The player can see the sword in

the merchant’s pocket.

• B. World of Warcraft, after player sells a

sword to a merchant for 100 gold coins, and then closes the trading

• window. When the player reopens the

trading window again, they can no longer see the sword in the merchant’ s pocket.

ANSWERS:

• A. Trader, just a simple transfer of ownership
• B. Converter (e.g. sword -> 100 gold coins

because it used up)

Production Mechanisms

Farmville

PRODUCTION MECHANISMS

• describes class of mechanics that make resources

available to player

• sources that bring the resource directly into player’s

hands, or e.g. facilities that gather resources from the landscape and make them available to player

• EXAMPLE: harvest vehicle collects a resources and

carries it to a refinery where it is converted into money that the player can use to buy other resources. The vehicle is the production mechanism.

Tangible and Intangible Resources

Roller Coaster Tycoon 2 Commander Keen: Goodbye Galaxy

TANGIBLE AND INTANGIBLE RESOURCES

• if resource possesses physical properties in game world

it is tangible (eg. ammo in FPS)

• if resource occupies no physical space it is intangible

(eg. money in Roller Coaster Tycoon)

Feedback Loops, Mutual Dependencies and Deadlocks

FEEDBACK LOOPS, MUTUAL DEPENDENCIES, AND DEADLOCKS

• production mechanism that requires some of the resources that

the mechanism itself produces, feedback loop

• if the system runs out of the resource, the mechanism can not

produce more, deadlock unless designer allows another way to break the deadlock

• If resource B need to produce entity A and A is the only

entity that produces B. If there is not enough of resource B to produce A then there is no way to get B anymore.

• Provide other way to get B to avoid deadlocks (Design

rule: provide means to break deadlocks)

• two production mechanisms that require the other’s output as

their input in order to work are mutually dependent, if the resources produced by either one are stopped, production stops for both

Static Equilibrium

STATIC AND DYNAMIC EQUILIBRIUM

• static equilibrium state in which amounts of resources produced

and consumed remain the same

• settingling into state of equilibrium takes pressure off the player

and allows them to watch the game run for a little while

EXAMPLE:

• Suppose you have a miller grinding wheat to make flour and a

baker baking bread from the flour. If the bakery consumes the flour at exactly the same rate at which the mill produces it, then the amount of flour in the world at any one time will remain static. If you close the bakery for a while, the flour will build up. When the bakery restarts, the amount of flour available will be static at the new

• level. The system

returns to static equilibrium because the key factors—the production and consumption rates of the mill and the bakery have not changed.

Dynamic Equilibrium

STATIC AND DYNAMIC EQUILIBRIUM

• dynamic equilibrium when the system fluctuates through a

cycle, constantly changing, eventually returning to a starting point and begins again EXAMPLE:

• Let’s suppose that only one person does both jobs. She mills

enough to bake three loaves of bread; then she bakes the three loaves; then she mills again; and so on.

• This is an example of dynamic equilibrium: Conditions are

changing all the time, but they always return to the same state after a while because the process is cyclic. If we tell the woman to stop baking and only mill for a while, and then resume baking later, again the flour builds up. When she resumes baking, the system settles into a new state of dynamic equilibrium

Challenges & the Core Mechanics

Super Meat Boy Chips Challenge

CHALLENGES AND THE CORE MECHANICS

• core mechanics implement mechanisms by which most

challenges operate, and perform tests to see if challenge has been beaten Example:

• 1. Super Meat Boy - Passive challenge to get across

gap

• 2. Chips Challenge - Teeth, is a monster that follows

Chip wherever he goes, but only move every other turn. Which turn they start to move on is dependent on odd and even step. The teeth has an almost sentient programming, which makes it the most complex monster in Chip's Challenge.

Passive Challenges

Brendan Sim - 3GB3 Assignment 2

PASSIVE CHALLENGES

• example: static obstacle, such as a wall that avatar

must climb over

• mechanics only implement action of player, not

presenting challenge itself

• may create a special event that occurs once avatar

arrives on other side of the wall

Active Challenges

Final Fantasy XIII-2

ACTIVE CHALLENGES

• example: puzzle
• must have entities and mechanics to define puzzle,

player interaction, and display consequences

• Mechanics that allow the player to interact with it

and display consequences of his/her actions.

Actions and Core Mechanics

Battlefield 4

ACTIONS AND THE CORE MECHANICS

• actions available to player do not change from level to

level (usually) PLAYER ACTIONS TRIGGER MECHANICS

• must specify mechanic that implements each action,

which will initiate an event or start/stop a process

• 1. UI detects data arriving from input device
• 2. UI then determines what action the player desires

by checking the assignment of actions to control devices

• 3. UI then triggers whatever mechanic associated.

EXAMPLE: if user presses button assigned to crouch, UI triggers crouch mechanic mechanic does 2 things

• 1. changes posture attribute from walking

upright state to crouching state

NOTE: this may affect other mechanics, (e.g. when jump is applied in crouch state)

• 2. feedback, mechanic lowers value of

numeric height attribute (detected by graphics engine and displayed) ACTIONS ACCOMPANIED BY DATA

• more complicated actions may involve

manipulation or storage of data from UI

• designer must create both an event mechanic that

implements the action and an entity that stores the data

• EXAMPLE: 1st person game, player uses mouse

movement to control direction and movement of avatar

• mouse contains more info than controller

button, UI sends data about how far mouse is moved

• requires mechanic to interpret data, and make

appropriate changes

Core Mechanics Design Tips

Goals of Core Mechanics Design

• Strive for simplicity and

elegance

• Look for patterns, then

generalize

• Do not try and get

everything right on paper

• Find the right level of detail

CORE MECHANICS DESIGN

• designing core mechanics consists of identifying key

entities and mechanics in the game and documenting them

• 1. GOALS OF CORE MECHANICS DESIGN
• never forget ultimate goal is to create entertainment for the

player STRIVE FOR SIMPLICITY AND ELEGANCE

• avoid making mechanics too complex, want it to be

easy to learn to play games LOOK FOR PATTERNS, THEN GENERALIZE

• learn to recognize patterns in your ideas for your game

and convert them into generalized systems

• don’t make the same creature over and over with

similar mechanics, design one idea with mulitple supporting mechanics

Example:Swamp leeches should lose 10 points health for every minute out of water Salamanders should lose 5 points of health for every minute out of fire Pattern: ALL creatures in game need 2 attributes:

• 1. symbol indicating native environment

(water, fire…)

• 2. numeric attribute stating rate of health loss

(should be 0 if not environment-dependent) DON’T TRY TO GET EVERYTHING PERFECT ON PAPER

• hard to map out everything on paper, cannot compute

effects of all mechanics in your head

• make a first draft, then build prototype (can be in

spreadsheet) to test FIND THE RIGHT LEVEL OF DETAIL

• the more detail you put into your core mechanics

documentation, the quicker the programmers can code BUT it is not the designers job to work that closely on implementation, it takes too much time

• you must find a happy medium where the

programmers know what to do but still avoids

• verloading yourself

Core Mechanics Design Tips

Revisit your earlier design work

• Reread your work to identify entities and mechanics,

list nouns and verbs

• Noun - entity or resource
• Verb - mechanic
• 2. REVISIT YOUR EARLIER DESIGN WORK
• reread your work to identify entities and mechanics, list

nouns and verbs

• noun - entity or resource
• verb - mechanic

Important phrases:

• if, when, whenever
• Your answers to the question, “What is the player

going to do?”

• Your flowboard of the game’s structure
• Your list of gameplay modes and your plans for

them.

• The general outline of the story you want to tell
• The names of any characters

• Your general plans for each level in the game
• The progression of the levels - sequence of levels,

information stored in entities between levels

• Any victory or loss conditions
• Any non-gameplay actions - virtual camera, pause
• r save game
• 3. LIST YOUR ENTITIES AND RESOURCES
• break down your nouns into resource, or entities
• break down your entities into simple or compound

simple: symbolic or numeric? symbolic: what states can it take? numeric: what is the range of numbers? what will its initial value be?

Core Mechanics Design Tips

Add the Mechanics

• Think about your resources
• Study your Entities
• Analyze challenges and Actions
• Look for global mechanics

ADD THE MECHANICS

• every relationship must be defined, remove words like

somehow THINK ABOUT YOUR RESOURCES

• think about how they flow through the game

how do they enter? what drains them? conversion rate? STUDY YOUR ENTITIES ■ Does this entity store an amount of a resource, and if so, have I already documented how it works in the previous step? ■ What events, processes, and relationships affect the entity? What conditions

apply to these events, processes, and relationships? ■ What events, processes, and relationships does the entity contribute to? What conditions apply to them? ■ What can the entity do by itself, if anything? Any entity that can do something by itself—whether the entity is as simple as a detector or as complicated as an NPC—requires mechanics to define what it does and how. ■ What can the player do to the entity, if anything? If the player can manipulate the entity, he requires an action to do so, and actions require mechanics. ■ Is this a symbolic entity? If so, it requires mechanics to control how the entity gets into each of its possible states.. ANALYZE CHALLENGES AND ACTIONS

• go over list of challenges and actions
• ensure all active challenges have an associated

mechanic LOOK FOR GLOBAL MECHANICS

• global mechanics operate all the time, eg. victory or

loss condition