Core mechanics

1. FUNDAMENTALS OF GAME DESIGN
CORE MECHANICS
Sayed Ahmed
BSc. Eng. in CSc. & Eng. (BUET)
MSc. in CSc. (U of Manitoba)
http://sayed.justetc.net
http://www.justETC.net
sayed@justetc.netWww.JustETC.net
Presented at the University of Winnipeg, Canada
Just E.T.C for Business, Education, and Technology Solutions
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2. 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

3. 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)

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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)

16. 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

17. 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

18. 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

19. INTEGRATION: NUMERIC AND SYMBOLIC RELATIONSHIPS
 Your game may need to change the state of
symbolic entities based on numeric entities

20. 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

21. 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

22. 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

23. THE INTERNAL ECONOMY
 Feedback loops, Mutual Dependencies, and
Deadlocks
 Need some input resources to produce something
 Think about deadlock
 Static and Dynamic Equilibrium

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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

32. 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

33. THE GAUSSIAN CURVE

34. THE GAUSSIAN CURVE
 Most things lie somewhere in the middle
 Rare things lie in the extremes

35. 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