F UNDAMENTALS OF G AME D ESIGN C ORE M ECHANICS Sayed Ahmed BSc. Eng. in CSc. & Eng. (BUET) MSc. in CSc. (U of Manitoba) Presented at the University of Winnipeg, Canada Just E.T.C for Business, Education, and Technology Solutions 1

C ORE M ECHANICS 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

T OPICS 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)

T OPICS How to design core mechanics By reexamining early design work Render it specific and concrete Discuss random numbers How to use them in Games

F UNCTIONS OF THE C ORE M ECHANICS IN O PERATION 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

F UNCTIONS OF THE C ORE M ECHANICS IN O PERATION 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

F UNCTIONS OF THE C ORE M ECHANICS IN O PERATION 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

R EAL -T IME G AMES V S. T URN -B ASED G AMES 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

R EAL -T IME G AMES V S. T URN -B ASED G AMES 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

C ORE -M ECHANICS AND L EVEL 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

K EY C ONCEPTS 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

K EY C ONCEPTS 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

K EY C ONCEPTS 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

K EY C ONCEPTS 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

K EY C ONCEPTS 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)

R ELATIONSHIPS AMONG E NTITIES 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

K EY C ONCEPTS 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

R ELATIONSHIPS 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

I NTEGRATION : N UMERIC AND S YMBOLIC R ELATIONSHIPS Your game may need to change the state of symbolic entities based on numeric entities

T HE I NTERNAL E CONOMY 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

T HE I NTERNAL E CONOMY 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

T HE I NTERNAL E CONOMY 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

T HE I NTERNAL E CONOMY Feedback loops, Mutual Dependencies, and Deadlocks Need some input resources to produce something Think about deadlock Static and Dynamic Equilibrium

C ORE M ECHANICS AND G AME P LAY 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

C ORE M ECHANICS D ESIGN 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

C ORE M ECHANICS D ESIGN 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

R ANDOM N UMBERS AND THE G AUSSIAN C URVE 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

P SEUDO -R ANDOM N UMBERS 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

M ONTE C ARLO S IMULATION 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

M ONTE C ARLO S IMULATION 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

U NIFORM D ISTRIBUTION 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

N ON U NIFORM D ISTRIBUTION 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

T HE G AUSSIAN C URVE

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

S UMMARY 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