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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.nethttp://www.justETC.net
ww.JustETC.net
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