Mechanics & Gameplay
Ce217 – Computer Game design
7th February, 2017
Prof. Richard A. Bartle
introduction
• Today’s lecture concerns game
mechanics and gameplay
• Games are dynamic systems
– They have moving parts
– These moving parts are their mechanics
• Mechanics are about causality
– If/when you do this, then this will/could
happen
• A fEedback loOp is a mechanic (see later)
• A leaderboard is not a mechanic
But first ... dressing
• Mechanics describe games in terms of
their engineEring
• DresSing (or skin) describes them in
terms of their fiction
• Note that Games are not about
mechanics, they’re about gameplay
• Take away the dresSing and the
mechanics are what’s left
– Abstract games have very liTtle dressing
– they’re only about the mechanics
An analogy
• It’s Like with a car: the colour and
styling don’t affect the workings of
the internal combustion engine much
– THE engine is mechanics, the colour isn’t
• Of course, many people do buy cars
based on how they look
– They only notice the mechanics when they
fail…
• Did I mention that the word is spelled
LOSE?
Not undressing
• Dressing is strictly to do with the
fiction of the game
• The following are not changes to
dressing:
– Changing the representation of the
tokens, for example from dice to cards
– Adding an external context, so the game is
identical but eg. “players pretend to be pirates”
• Changing what the tokens mean is
changing its dressing
combination
• Dressing gives a game its fictional
context
• there’s a relationship between
mechanics and dressing
– the context can come from the mechanics
– The mechanics can come from the context
– They can both come at the same time
• It’s just about posSible that the two
are so intertwingled that you can’t
actually separate them
• Almost always you can, though
Separation 1
• Why would you want to separate them?
• Because the context can get in the way
when figuring out gameplay issues
– “but IRL people need to eat and drink…”
• Because if you understand the mechanics of
one game, you can use them for
another
– I know! Let’s make a game called gardenville!
• Because no matter how flashy the
graphics, no mechanics means no game
Separation 2
• Why would you not want to?
• Because a Mismatch between mechanics
and dressing can spoil the game
experience
example
• From raph koster, a theory of fun
Tetris!
Art (again)
• Context and mechanics are both ways
that
designers
say
things to
players
so
• So it’s useful to separate mechanics and
dressing, but dressing is important
– It’s esSential if you want iMmersion
• So how do you strip away the context?
• Let’s consider a game
you know – frogger
start
• At the start in frogger, you’re looking at
lines of trafFic moving in front of you
– Made up of different vehicles with different
length gaps between them
• Each line moves at a steady rate and in
a single direction
– But Rate and direction may differ between lines
• You can move your frog in any direction
– at the same speed as the fastest vehicle
• If a vehicle hits your frog you lose
Without context
There are lines of on/off paTterns
Repeats of on and off vary per line
Each line moves smoothly left or right
spEed of movement varies across lines
You move a token among the lines
Your token moves at the maximum
speed that a line can move
• If your token is co-located with an
on setting then you lose
•
•
•
•
•
•
abstract
• Now reading that previous slide on its
own, it would be tricky to tell what
game it described
– you would have been hard pressed to figure it
was about frogs trying to cross traffic
• It describes the main mechanic of
frogger, without hinting at the context
• This makes it easier to re-use
• The level of abstraction I chose to
use also makes a difference
detail
• I could have gone into more detail
with this
–
–
–
–
Describe the map as a grid
Describe movement speEd as squares/second
Say how many lines there are
State the paTterns for the lines
• Also, I could have covered more than just
the first part of frogger
• The reason I didn’t was because of wow
wotlk’s naxxaramas dungeon…
naxxramas
copying
• As you may have gueSsed, this section
of naxxramas uses the same mechanic
• There are differences:
–
–
–
–
Slimes only move left to right
The speed is the same for aLl slimes
Players get to rest between lanes of slimes
It’s multi-player, so other players who
get slimed can make it easier for you
• Basically, though, it’s frogGer
• The players refeRred to it as frogger!
reskinning
• Wow Wotlk Naxxramas used one of
frogger’s mechanics
– Ok, so it was the main one, but frogger
does have others
• Sometimes you can use all of them
• if you do use them all and don’t add
any others, This is called reskinNing
– I described koster’s reskinned Tetris earlier
• Even abstract games can be reskinned
– The 1 to 9 game from lecture 1 was a
reskiNned 0s and xs
Game idea
• If aLl you have to your design is a
mechanic, there’s little skin to re
• Adding some dressing to these is basically
a marketing decision
• There are many boardgames that are
purely abstract in nature which have
been cast as something more EXCITING so
as to seLl
– Ancient mythology, pirates and historical
TOWNs are particularly popular
Lost cities
• Reiner knizia, 1999
analysis
• Lost cities has 5 suits and no aces, but
it’s pretty obvious where its origins lie
• It was developed using playing cards,
then modified
– So you couldn’t just use an ordinary
pack of cards to play it
– So it had an appealing subject
• Really, though, the dressing is just an
add-on to the mechanic
– It’s a good game, though!
Besikovitch’s game
• Here’s a card game that has no skin
• The Two players Take one suit each
from a pack of cards as their hand
• A third suit is shuffled and turned
face up
• Players simultaneously bid one card from
their hand for the top turned-up card
• Higher bid adds the card to their trophy
pile; both players lose their bid cards
– 13 hands later, total the points in your
trophy pile, highest wins the game
Re-use
• Besikovitch’s game has perfect information
and symMetrical starting positions
– Abram Samoilovitch Besicovitch (1891-1970) was a
mathematician…
• Remember the war of the roses game idea I
came up with in lecture 2?
• I had the mechanics of besikovitch’s game in
mind when I did it
– I also used it in a web game, spymaster
• Do I feel guilty for ripPing besikovitch oFf?
• No, because he himself ripped the mechanic off
from the russian card game Svoi Kozyri
evolution
• Mechanics are like a game’s dna, and they
often
evolve
from
earlier
games
formalisms
• Because it’s possible for multiple games
to share mechanics, wouldn’t it be
great if we had some way of writing
them down and comparing them?
– Like we do music, dance, mathematics, …
• Yes, it would be great! But we don’t
yet have any such formalism
– Not even for limited domains such as 2player card games
• Maybe if you want a phd..?
Beyond mechanics
• I’ve talked about mechanics here, but
how do you get from them to
gameplay?
• Well, mechanics are part of a
hierarchy that spans from a game’s
components to its gameplay
• Gameplay is the FUN part; the others
build up to it
• The hierarchy won’t fit on this slide so i
guess I’d better start another...
Hierarchy (from bottom)
• Tokens (aka entities)
– Gameplay-significant objects – “nouns”
• Rules
– What you can do to tokens – “verbs”
• Features
– Ways of organising tokens
– Emergent from rule interactions
• Gameplay
– Emergent from feature interactions
emergence
• Before I go through this list, a quick
word on emergence
• Emergence is where something aPpears
from other things’ combined efFects
• Example:
– Rule 1: drive on the left
– Rule 2: give way when joining a road
– result: go clockwise on roundabouts
• Can be plaNned or unplaNned
• Can be bugs or (ahem!) features
tokens
• Tokens are those things in the game
which can act or be acted upon
– Objects, buildings, npcs, pcs, environment, …
• Game rules directly concern tokens
– Game features are ways to organise
tokens, emergent from the rules
• In computer games, tokens are usually
the programMing objects
– They may have associated asSets (lecture 7)
– They may have associated properties
rules
• Rules refer to tokens and each other
• Features emerge from rule interactions
• Example:
– Rule 1 – artillery kills infantry with no cover
– Rule 2 – artillery makes craters
– Rule 3 – craters provide cover for infantry
• The emergent feature is “defences need
to be managed”
• Rules Together with features form The
mechanics by which gameplay emerges
features
• Features are what makes this game
different to other games
• In terms of mechanics, It Usually
means ways to organise tokens
– It Can mean ways to organise rules, when
rules are tokens
• Features emerge from interactions
between game rules
– As each says a diFferent thing about tokens
• Gameplay emerges from interactions
between features
Other features
• Important: the word “feature” is often
used in the more general sense, too
• i’m talking formal features right now,
but there are also informal features
–
–
–
–
–
“realistic graphics”
“free to play”
“made for pre-schoolers”
“available on macs”
“unique quest system”
• With no context, This can be confusing
– both uses are correct!
Features from Use cases
• Use-case driven design involves uml
– Unified modelling language
• I’m hoping you’ve been taught this!
• draw the central concept in a triangle
then write major functionality nearby
– Add more for each such piece of functionality
• A way of brainstorming your feature set
– Through writing tokens, rules and features
• Helps Identify core activities
– Made up of the many individual actions the
player performs – use cases
Example:
• From bethke’s book
xp
Hit pts
dragons
NPCs
races
pcs
magic
monsters
music
RPG
vo
trade
potions
swords
Good v evil
lanterns
towns
levels
weather
ruins
Types of feature
• integral features
– Vital to working of the game
– Eg. quests in RPGs
• Which do you do next, which do you abandon?
• Chrome
– Enhance look & feel but don’t affect gameplay
– Eg. character model creation
• Gameplay substitutes
– Multiple near-identical choices – bad idea
– Eg. 23 different kinds of sword
gameplay
• In the same way that features emerge
from rule interactions, gameplay
emerges from feature interactions
– And thence from rules and tokens
• Gameplay: “a series of interesting choices”
– Sid meier
– what players do in the game to have FUN
• There are subjective degrEes of gameplay
– Some games have “more gameplay” than others
– Snakes & ladders v bridge
Example (from lecture 2)
• “It’s a wild west game with cowboys
and cattle and fields and bandits”
– These are tokens. What’s the gameplay?
• “cowboys consume coffee and beans.
Cattle live in fields. Cattle is sold in
town. Coffee, beans and ammunition are
bought in town. Bandits rustle cattle.
Cowboys with ammunition can shoot
bandits.”
– These are rules. What’s the gameplay?
example
• “herd sizes must be balanced. Cowboy
numbers must be watched. Supplies
must be pre-ordered.”
– These are features. What’s the gameplay?
• “you supply your cowboys in the fields
with cofFEe and beans, they raise your
catTle which you take to market and seLl
so you can buy more land, more coffee
and beans, and guns to fend off bandits”
– That’s the gameplay!
More formal example
• Let’s look at the classic game rogue:
• Tokens:
– The rogue, monsters, (hit points), coins, magic
items/weapons, squares, rooms, passages, doors,
secret doors, steps.
• Rules:
– [R1] When the rogue and a monster attempt to share
a square, they do damage to each other.
– [R2] When the rogue or a monster reaches zero hit
points, it dies.
– [R3] Hit points recover slowly.
formal example 2
• Rules (continued):
– [R4] Magical weapons do more damage than ordinary
weapons.
– [R5] Only coins count towards the final score.
– [R6] Lower floors have more coins.
– [R7] Lower floors have more magical items.
– [R8] The deeper the level, the more hit points the
monsters there have.
– [R9] The rogue and monsters move.
– [R10] Treasure doesn’t move.
formal example 3
• Features:
– [F1] Players must manage the need to obtain
coins, bearing in mind the danger of
confronting monsters [R5 v R1].
– [F2] Players must balance the risk of
going to a lower level with the rewards of
greater treasure on that level [R6, R7 v R8].
– [F3] Players must consider the chance of
finding treasure in comparison with the
chance of being surrounded by monsters [R9 v
R10].
formal example 4
• Gameplay:
– Players attempt to find the steps to the
next level as soon as they can so they have an
escape route [F2 v F3], then try to clear
the level while avoiding the toughest
monsters [F1 v F3], in order to level-up and
gear-up to increase their survivability
[f1 v F2], so they can maximise their coins.
• You should be able to do something
similar for any game to derive its
gameplay
interactivity
• Key to gameplay is interactivity
– With the game environment
– With other players
– With NPCs
• taken from player’s point of view
– NPCs interacting with the environment don’t
qualify a game as “interactive”
• Interactions change that with which you
are interacting
– They Produce a new range of choices
On mechanics
• When designing gameplay, you combine
mechanics so that the gameplay emerges
– Knowing some mechanics therefore helps...
• Most people do know some basic
mechanics anyway
– Ones based on Taking turns, betting, bidding,
matching, building, ...
• You make mechanics by putting together
sets of mutually-compatible rules
– Complex Rules can be mechanics directly
examples
• Example: in a platformer, you can jump
– Rule: If you miSs your jump you die
– Rule: If you land on an enemy you kiLl it
• Together they’re a jumping mechanic
• Example: in an rpg you can cast spelLs
– Rule: some spells take time to cast
– Rule: some spells impair their targets
– Rule: you can’t cast spells while impaired
• Together they’re an interRupt mechanic
loops
• Those two mechanics emerged from rule
combinations, not interactions
– Therefore they’re not features
• analogy: it’s like a function made up
from calls to suPport functions
– It’s a higher function, but still a function
• Now If this function is recursive, that
makes it a loOp
• Two loop mechanics are particularly
important for game design
Positive feedback loop
• In a positive feedback loop, the betTer
you do then the easier it becomes
– Example: monopoly
• Your lead will increase If being ahead
gives you an advantage
• Unstable and Not good betwEen players
• Can be good if it affects everyone
– They pull ahead of where they were together
• Can work for short events with an end
– Stun locks in combat
Negative feedback loop
• In a negative feedback loop, the beTter
you do then the harder it becomes
• Your lead will decrease If being ahead
gives you a disadvantage
• Very good at aLl levels of gameplay
• The Main danger is that it could act as
too much of a dampener
– Skill becomes irRelevant to victory
• Therefore use graduated feedback
– it Only really kicks in if you get way ahead
social mechanics
• Note that mechanics don’t have to emerge
from writTen rules
– UnwriTten rules can play a part, too
• Example: diplomacy
– The supPort mechanic
•
•
•
•
We simultaneously give orders to our units
Units can be ordered to move or suPport
A unit is dislodged if it has lesS support
Units can support units of other players
– The alLiance mechanic
• I’ll help you if you help me (until i stab you)
The Core mechanic
• All games have at least one mechanic that
players do rhythmicalLy throughout
• This is that game’s core mechanic
– Sometimes called the core loOp
– sub-games may have their own core mechanics
• It usually involves 2+ mechanics per beat
– In a platformer it’s moving & jumping, in
a fps it’s moving & shooting, in a soccer
sim it’s movement & passing, in werewolf
it’s killing & lynching, in go it’s placing and
capturing, in tenNis it’s moving and hitting
design
• So where do particular tokens, rules,
features and gameplay come from?
• There are two ways to write a story:
– Sit down and start writing
– Plan it in advance
• The same thing applies to creating a
computer game
– Sit down and start prograMming
– Plan it in advance
• Both are forms of design
Without a plan
• Start with an idea
– “a wild west game”
• By programming it, you are forced to
make concrete decisions
– “How am I going to implement horses?”
• This gives you more ideas
– “this could be a game about herding cattle”
• It Takes you in unexpected directions
– Which are expensive to undo if these are
wrong directions!
With a plan
• Also start with an idea
– “a wild west game”
• Consider wider consequences of idea
– “horses & cowboys & guns & cavalry & …”
• Engage in flights of fancy until
something suddenly seems right
– “players are outlaws fighting injustice”
• iT takes you in expected directions
– Which may prove to be wrong directions
when they’re finally coded
In practice
• Top down (plan) v bottom up (no plan)
– Remember the Macho women with guns example
• Better games from an organic approach
– plan, test, replan, restest, throw away, add, …
– “sid graphics”, prototypes, prototyping tools
• But Programming is expensive, so you
don’t want to do it uNneceSsarily
• a plan means resources can be allocated in
advance of when they’re needed
• most publishers therefore want a plan
– In the form of a design document
Aside: originality
• What colour are health and mana bars?
• In general, health bars are red or green
(colour blind) and mana bars are blue
• If there’s no mana bar?
– the health bar will be green but get yellow
then red as damage is taken
• These are examples of comMonalities
of design across games – and they’re ok!
– Players expect it
– If you don’t follow the herd for your ui,
there’d better be a good reason!
Dominant strategy
• Good-looking Gameplay can be spoiled by a
dominant strategy
– One so effective that doing anything else is
pointleSs
– The Player’s experience changes liTtle from
one game to the next
• Example: unit rushes in Multi-player Age of
Empires (or any other rts…)
• A dominated strategy is wasted
• A dominant strategy wastes aLl the rest!
Nice dress...
• From dragon’s dogma:
Near-dominance
• A near-dominant strategy is one
that players will use most of the time
– A near-dominated strategy is one they’ll
only use under very naRrow circumstances
• A game with a near-dominant strategy is
better than one with a dominant strategy
– Because timely switching to the right neardominated strategy is itself a strategy
• The gameplay is Still usually better if
dominance is not there at aLl, though…
victory
• Gameplay doesn’t require a victory
condition
– “how do you win?” is a different question to
“what’s the gameplay?”
• Some games (eg. most virtual worlds) are
designed to have no victory condition
– You can’t win wow, eq, sw:TOR, eve, TSW, …
• Even so, gameplay is progreSsive
– play, save, screw up, reload, replay, save, …
– You Need a sense of how weLl you’re doing
Replay value
• Note that There’s a correlation between
good gameplay and good replay value
• play the same game multiple times and
get a difFerent experience for each one
• Ways to increase replay value include:
–
–
–
–
Random but coherent maps
Large numbers of pre-supplied scenarios
Editor, so players can create own scenarios
Game changes during play so the end has
different gameplay from the beginning
Assignment!
• Ok, to progress your assignment at a
reasonable pace, this week you should
write the sections for:
– Tokens
– Rules
– Features
• Note that the features here are formal
features, emergent from rule interactions
– NOT the everyday meaning of the term!
• Each of these three sections is worth
5% of the total mark for the assignment
Assignment notes
• You should conNect these
• For tokens, just give a representative list
– or a list of types if you have many tokens
• For rules, list 5 or more main rules
– Ensure that all the tokens the rules refer
to are in your tokens list
– Number the rules
• For features, list at least 3
– state them in terms of the rules they emerge
from (which is why I said to number rules)
– Like I did for rogue
And finally…
• If you just want definitions
– http://www.gametheory.net/dictionary/DominantStrategy.html
• If you don’t have bethke’s book…
– http://www.gamasutra.com/view/feature/2872/structuring_key_de
sign_elements.php
• Guess which of these is a reskiNning of the
other
– http://www.youhaventlived.com/drlivingstone/index.html
– http://www.youhaventlived.com/spunkyprincess/index.html
• What’s the diFference?
– http://www.ferryhalim.com/orisinal/g2/rope.htm
– http://www.newsgaming.com/games/madrid/
NSS
• National student survey!
– Have your say about essex university without
essex university having a say in what you
say…