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FUNDAMENTALS OF GAME DESIGNCORE MECHANICS

Sayed AhmedBSc. Eng. in CSc. & Eng. (BUET)

MSc. in CSc. (U of Manitoba)

http://sayed.justetc.net

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Presented at the University of Winnipeg, Canada

Just E.T.C for Business, Education, and Technology Solutions

CORE MECHANICS

Core Mechanics Determine how a game actually operates What are the rules of the game How the player interacts with them Defines the game play

TOPICS Understanding Core-Mechanics Designing Core Mechanics Explain the role of core mechanics in providing

entertainment How core-mechanics differ between real time and

turn based games How core mechanics are related to level design Key elements of core-mechanics

Resources, entities, and mechanics How you may use them to define rules precisely

Specific implementation of core mechanics In the internal economy of games

A set of mechanics that governs the flow of quantities How designers use mechanics

To create game play (challenges and actions)

TOPICS

How to design core mechanics By reexamining early design work Render it specific and concrete

Discuss random numbers How to use them in Games

FUNCTIONS OF THE CORE MECHANICS IN OPERATION

Operate the internal economy of the game Present active challenges Accept player actions Deter victory or loss Operate the Artificial Intelligence Switch the game from mode to mode Transmit triggers to the storytelling engine

FUNCTIONS OF THE CORE MECHANICS IN OPERATION

Operate the internal economy of the game Most important role of the core mechanics Specifies

how the game or player creates, distributes, and uses up the goods on which the game bases its economy

Present active challenges To the player via the user interface Active: governed by the core mechanics Passive: A chasm that the player must jump over

Accept player actions From the user interface Implement the effect on the game world

On other players as well

Detect victory or loss Detect condition for victory, loss, termination Detect success or failure in all challenges

and apply consequences

FUNCTIONS OF THE CORE MECHANICS IN OPERATION

Operate the Artificial Intelligence Operate the NPCs and artificial opponents

Switch the game from mode to mode Keep tracks of modes Changes game play mode Signal User Interface engine to update UI

Transmit triggers to the storytelling engine Trigger story telling engine to weave story

REAL-TIME GAMES VS. TURN-BASED GAMES

Real-Time Games Most games operate in real time

The game advances with time All players simultaneously play the game

In multiplayer games

Turn-Based Players Take Turns

Real-Time Core mechanics specify the parameters of a real world

that operates on its own whether the player acts or not

Processes operate continuously NPCs do and act what they are supposed to do Banks collect interest One shot event – may happen at players action only

REAL-TIME GAMES VS. TURN-BASED GAMES

Turn-Based Usually no NPC The core-mechanics do nothing until a player

take his turn Once a player is done the core mechanics can

compute the effect Then core mechanics remain idle until the next

player takes his turn You may define processes

But will only work in between players turn

CORE-MECHANICS AND LEVEL DESIGN

Level design What challenges each level will contain

Core-mechanics How challenges work in general But not exactly which challenges each level will

contain But sometimes you may cooperate with level

designers

KEY CONCEPTS

To design core mechanics You must document the different components

that define how your game works Find out the relationship among them

Resources Entities

Simple Entities Compound Entities Unique Entities

Attributes of Entities Mechanics

KEY CONCEPTS Resources

Types of objects or materials the game can move or exchange The game handles as numeric quantities May be also water – not countable

Does not refer to specific instances of these objects But the type itself

Core mechanics define the processes by which the game creates, uses, trades, and destroys resources

Rules by which Specific instances of resources

Can legally be moved from place to place Owner to owner Can come into and go out of the game

Non-physical concepts Popularity, resistance to poison as resources Try to quantify them as numbers so that you can manipulate them

KEY CONCEPTS

Entities Particular Instance of a resource State of some element – light – symbolic value Building, character, animal State of a traffic light Simple Entities

Specified by single value Score, state of a light Identify simple entities and define them in core mechanics

Compound Entities More than one data value to describe an entity Wind – speed and direction Each value = an attribute Avatar

A compound entity with another compound entity as attributes

KEY CONCEPTS

Entities Unique Entities

Only one entity of a particular type Avatar for example

Attributes of Entities An attribute is an entity that belongs to, and

therefore helps to describe, another entity Defining Entities for Your Game

Find out all entities in the game Define how to keep track of them Define how to represent them through user

interface Programmers will use these entities

KEY CONCEPTS

Mechanics Document how the game world and everything in it

behaves State

the relationships among entities The events and processes that take place among the

resources and entities of the game The conditions that trigger events and processes

Describe The overall rules of the game Behavior of particular entities

Operate throughout the game Apply only in particular gameplay modes Global Mechanic

Example: governs when the game changes from mode to mode (with help of entities that record what modes it is in)

RELATIONSHIPS AMONG ENTITIES

The value of one entity depends on the value of another entity They have a relationship Define it in your core-mechanics Numeric-entities: express mathematically Character levels

Experience points earned Character level = exp. Points * 1000

Events and Processes You state that something happens A change occurs Event

A specific change that happens once when triggered by a condition

KEY CONCEPTS

Events and Processes Process

A sequence of activities that once initiated continues until stopped

Conditions To define what causes an event to occur What causes a process to start or stop Conditional statements Define conditions in negative terms

Exception to general rules

Entities with their own mechanics Describe in terms of OOP

RELATIONSHIPS

Numeric Relationship is defined in terms of numbers and

arithmetic operations A bakery can bake 50 loaves of bread from one

sack of flour and four buckets of water Probability of an injury is directly proportional to

the weight and speed of the athletes Need familiarity with algebra and arithmetic

Symbolic What happens when a NPC sees the traffic light

to be Red, green, or yellow

INTEGRATION: NUMERIC AND SYMBOLIC RELATIONSHIPS

Your game may need to change the state of symbolic entities based on numeric entities

THE INTERNAL ECONOMY

An economy is a system in which resources and entities are produced, consumed, and exchanged in quantifiable amounts

Game designers: design and tune the game’s economy

Components Source Drains Converters Traders Production Mechanisms

Tangible and intangible resources Feedback loops, Mutual Dependencies, and Deadlocks Static and Dynamic Equilibrium

THE INTERNAL ECONOMY Source

A resource or entity can come into the game world where it was not before The mechanics by which it arrives is called source Enemies at the start, enemies spawn at different points

Each spawn point maintained by a mechanic Production rate Global mechanics Limited or Unlimited

Drains A mechanic that determines the consumption of resources Permanent drop out Shooting draining ammunition Being hit by enemy Consume, decay show a cause for draining

Converters Mechanic or entity Turns one or more resources into another type Production rate, input to output ratio Settlers: grain into flour, rate: one to one (bag) + 20 seconds

THE INTERNAL ECONOMY

Traders Mechanic that trades goods Stock trading game – financial construct, sword

trader Production Mechanisms

A class of mechanics that makes a resource conveniently available to a player

Sources that bring the resource directly into player’s hand

Characters to perform production Command & conquer

Tangible and intangible resources Tangible: Require physical space Intangible: No physical space required

THE INTERNAL ECONOMY

Feedback loops, Mutual Dependencies, and Deadlocks Need some input resources to produce

something Think about deadlock

Static and Dynamic Equilibrium

CORE MECHANICS AND GAME PLAY Challenges and the core mechanics

Passive challenges Not presented by core-mechanics – already there Can implement the actions, detection, and offer reward

Active challenges Offered by the core-mechanics A puzzle to open the door Define rules, actions, outcome

Actions and the Core Mechanics Player Actions Trigger Mechanics

Must specify a mechanic that implements each action in each gameplay mode

Initiate an event, start or stop processes Press a button, UI triggers a mechanic that implements the action,

mechanic – change the posture of the avatar – a symbolic attribute, determine and assign head position from ground

Actions Accompanied by Data Manipulation or storage of data Event mechanic and entity

CORE MECHANICS DESIGN

Goals of Core Mechanics Design Strive for Simplicity and Elegance Look for Patterns, then Generalize Don’t try to get everything perfect on paper Find the right level of detail Revisit your earlier design work

Answer questions such as what is the player going to do?

List your Entities and Resources Add the Mechanics Think About your resources Study your entities Analyze challenges and Actions Look for global mechanics

CORE MECHANICS DESIGN

Goals of Core Mechanics Design Strive for Simplicity and Elegance Look for Patterns, then Generalize Don’t try to get everything perfect on paper Find the right level of detail Revisit your earlier design work

Answer questions such as what is the player going to do?

List your Entities and Resources Add the Mechanics Think About your resources Study your entities Analyze challenges and Actions Look for global mechanics

RANDOM NUMBERS AND THE GAUSSIAN CURVE

Games use random numbers extensively Random numbers are usually generated as

>= 0 and < 1 In Statistics

Probabilities are always calculated between 0 and 1 You can use probabilities to

Generate events randomly Fix number of enemies Example: 10% times an event will happen

Generate a random number, if that’s <= 0.1 Execute the event

Weapon successful hit rating 80% (0.8) – to the aimed target Generate a random number, if that’s <= 0.8

Hit the target

PSEUDO-RANDOM NUMBERS

Random number generators (algorithms) usually use a seed If the seed is the same the sequence of the numbers

will be the same If a game always uses the same seed, the generated

numbers and the sequence will be the same all the time

Such numbers are called pseudo random numbers Useful for testing games

Bug fixing – can prevent bugs happening by chance Identify that changing the mechanics has affected the game

or not – fine tune core mechanics However, players play the game

Pseudo random numbers are not used Rather the seed is changed (current time), so that the

sequence of random numbers changes at each play

MONTE CARLO SIMULATION

You can test a system with two or few inputs easily Some direct mathematical relation may exist

But system that are dependent on too many factors May be hard to test Defining mathematical relationship can be difficult Still, using the mathematical relations to

understand and test the system may be difficult Rather you can take random input, and execute the

system, check the output Try to justify that the output makes sense or not If the output is logical or not If not, then you should work on more fine tuning

MONTE CARLO SIMULATION

A game tournament with 20 teams Difficult and time consuming

To make people play the game Test if the algorithms resemble fairness or not

Rather automate the game playing Select random inputs Analyze the output Think if the output made sense? Did the weak team defeat the strong team?

Did that happen very frequently – if so the game mechanics is not reasonable/fair – needs

fine tuning If it happened rarely – the game can be assumed to be

fair

UNIFORM DISTRIBUTION

Random numbers are generally generated with uniform distribution

The chance of getting any one number is exactly equal to getting any other number

Uniformly distributed die rolls Die roll = (random number * number of faces on

the die) + 1

NON UNIFORM DISTRIBUTION

You may want that Some values will be generated more frequently than

others For example,

You are designing a game: olympic shooting A player who came to play in olympics

Most of the times will hit a very close area• Than he will hit an area far from the center

An artificial player needs to be implemented that most of the times he hits a point close to the center

So the random number generation algorithm should Generate numbers where some numbers (the middle ones)

• Will show up more frequently than others Can be implemented as the sum of the numbers as

generated from Two or three dice rolls (at once) From two dice rolls: only one combination yields 2 but six

combinations (six possible ways) yield 7

THE GAUSSIAN CURVE

THE GAUSSIAN CURVE

Most things lie somewhere in the middle Rare things lie in the extremes

SUMMARY

By this time, you have a clear understanding of What core mechanics are What they do in games Mechanics consists of

Algorithms and data That governs the way the game is played

How to document core-mechanics In terms of

Resources, simple and compound entities Mechanics composed of

Events, processes, and conditions

Internal economy of games To define the movement of resources from

Place to place Owner to owner

Governed by mechnics