CHAPTER 10 CORE MECHANICS. CORE MECHANICS: -determine how the game actually operates -heart of the game -defines rules and game-play

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1 CHAPTER 10 CORE MECHANICS ZHONGSHI XI RACHEL MAILACH CORE MECHANICS: -determine how the game actually operates -heart of the game -defines rules and game-play

2 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 otherwise it will continue to fall. Tetris 1.68 D. The game is over when there is a block outside the boundary. 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

3 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. -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)

4 What the Core Mechanics Do Age of Empires -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 gameplay 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.

5 Real-time vs Turn-based Warcraft II Civilization 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

6 Core Mechanics and Level Design 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

7 Resources Star Craft 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 or resistance to poison as resources although in reality they can not be used as quantities that can be measured and be bought and sold.

8 Resources Settlers of Catan 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.

9 Entities Diablo 2 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.

10 Simple Entities SIMPLE ENTITIES -single value stored data can be numeric such as a score, or 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

11 Compound 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 objects in code

12 Quiz 2 Which of the following are entities, and which are resources? A. B. C. D. E. Money in Command and Conquer Number of Mario s lives in Super Mario Guns in Counter-Strike Crystals in Starcraft Sky in Sonic the Hedgehog ANSWER: A. Entity/Resource B. Entity C. Entity/Resource D. Entity/Resource E. Neither

13 Unique Entities FIFA 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

14 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 ANSWER: -No, if there are multiple avatars it is clearly not unique

15 Mechanics Hearthstone 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

16 Numeric & Symbolic Relationships Explore the two relationships in the game Angry Birds with respect to core mechanics. Angry Birds 1 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)

17 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 of 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 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

18 Event, Processes & Conditions Grand Theft Auto IV

19 Internal Economy Risk -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

20 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)

21 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

22 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

23 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

24 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

25 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

26 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)

27 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.

28 Tangible and Intangible Resources Commander Keen: Goodbye Galaxy Roller Coaster Tycoon 2 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)

29 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

30 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.

31 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

32 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.

33 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

34 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.

35 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

36 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

37 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

38 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 overloading yourself

39 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

40 -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 or 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?

41 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

42 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