examining the essentials of stealth game design

8/17/2019 Examining the Essentials of Stealth Game Design

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Examining the Essentials of Stealth Game Design

By Youssef Khatib [06.10.14]

This paper will look into the inner workings of stealth centric gaes to fin! out the

essential coponents of thistype of "i!eogaes. The paper will e#aine the history of such

gaes an! the !esign principles of stealth centric gaes in relation to the participating player.

To !o this$ one nee!s to fin! a suitable !efinition of what stealth centric gaes are. The

ost coon way is to !efine stealth gaes as genre.%ae !esign books categori&estealth gaes as a sub'genre of actiongaes. This way of categori&ing is present fore#aple in (rnest )!as an! )n!rew *ollings ,The Fundamental of Game Design

+,00-an! /cott *ogers Level Up! The Guide to Great VideoGame Design+,010. owe"er

this way of categori&ing gaes can cause soe confusion !ue to the way the action genre is

!efine!.

)n action gae is one in which the aority of challenges presente! are tests of the player2s

physical skills. +)!as$ *ollings$ pp.436$ ,00-

n the article Sorting Out the Genre Muddle, (rnest )!as e#plains the origin of gae

genre usage as sypto of the "i!eogaes in!ustry2s growth. )sore oney was beinga!e$the cost an! in"estents of !e"eloping new gaes increase! rapi!ly. 5nly large

publishers ha! access to store shel"es$ akingpublishers ore cautious of the content being

!e"elope! an! less willing to use creati"e approaches. /o "i!eogaes e"entually settle!into a set of genres recogni&e! as sports$ strategy$ racing$ fighting$ action$ role'playing$ an!

so on.+)!as$ ,007

/tealth gaes arecurrently recogni&e!as asub'category of the action genre.Thiscauses

probles because of the useof the wor! genre in arketing.

The retailers began organi&ing their shel"es along these lines. 8ublishers create! pro!uct

plans base! on the. %aers learne! to prefer one genre o"er another$ an! to i!entifythesel"es as fans of shooters or platforers or real'tie strategy. +)!as$ ,007

The unregulate! structure for the !efinition of the action genre causes probles$ !ue to its

lack of clarity. Therefore this paper will turn towar!s the 9:) +9echanics$ :ynaics$)esthetics ;raework +*obin unicke$ 9arc


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aesthetics.9echanics are functions that trigger actionsin the gaespace$ as se"eral

echanics interacting with each other this interaction is referre! to as the !ynaics of agae. These two coponents are often built an! !esigne! accor!ing to a !esire! aesthetic

goal.

*an!y /ith!efines stealth centric gaes asha"ing the following coonaestheticgoal>[To] create the illusion of a securely guar!e! area that the player can sneak through by "irtue of le"eraging their uni?ue abilities an! tools to create an! e#ploit security flaws>

+,006.n (rnest )!as2s !efinitions of challenge types$ stealth is a sub'category for

conflict challenges where the player is >a"oi!ing being seen> +)!as an! *ollings$pp.,3$

,00-. ;ro the abo"e one can!e"ise a ore precise !efinition of what stealth gaesare.This will be use! as a base for !ifferentiating stealth centric gaes fro other conflict

centric gaes.

•1.1 Purpose

Thepurpose of this paper is to failiari&e the rea!er with stealth'centric gaes an!to!ifferentiate thefro action gaes$by e#aining siilarities between stealth gaes an!

the aesthetics they aspire to$ as reflecte! in their echanics.

•1.2 Question

@hat are stealth centric gaes$ how are they !esigne! an! whatattributesare essential for

a!hering to their aesthetic goalA

•1.3 Scope of work

There are any instances where these gaes !e"iate fro their stealth centric approach.This happens when they intro!uce cobat centric scenarios for the purpose of con"eying

the o"erarching narrati"e of the gaeworl! an! a prie e#aple is when boss encounters

happenin whichplayers are presente! with a set of e#pectations unlike the !efault

challenges present in the gae. This paper will only focus on theain proce!ure of play for these gaes an! not the atypical challenges foun! in boss battles.

•2. ackgroun!

/tealth gaes are wi!ely thought to ha"e starte! with Metal Gear for the MS"# hoecoputer in 17-. owe"er the earliest known gae with stealth eleents was release! as

early as 171 with Castle @olfenstein+9use /oftware.@orthy of note is that any of the

echanics intro!uce! early on$ like hi!ing !ea! bo!ies an! frisking guar!s for ites$later!isappeare! fro newer gaes for soe tie an! !i! not resurface until !eca!es later.

The year 177 saw the release of se"eral titles that a!e use of stealth systes. 9any of

these gaes becae coercial successes allowing this style of play to reach new


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au!iences pre"iously unaware of this type of gae systes. :uring this tie$ any of

these gaes e"ol"e! further$ by borrowing echanics an! eleents fro other non'stealthcentric gaes.

By the turn of the illenniu$ stealth centric gaes starte! gaining oentu with

releases like Thief $$TheMetal %ge+


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ow o"eent is !esigne! "aries greatly in these gaes an! is !epen!ent on how the

!esign approaches the subect of sneaking.

Conteporary stealth centric gaes re?uire the player to anipulatethe spee!at which theytra"el through the gae'space$without alerting any threats. This type of gaes offers

echanics to alter the pace of o"eent by ipleenting !ifferent walk an! run o!es.These o!es can either work as !ifferent states or in transition fro one totheother.;urtherore$ these o!es can alter the a"atar2s stance. (arlier gaes of stealth ten!e!

to only ha"e one o!e of o"eentE this eant that in early gaes guar!s generally !i!

not ha"e cople# systes for sensory perception.+/ee artificial intelligence section 6.1.,

/itman 'odename 01 +(i!os $,001 akes use of a echanic calle! >Snea-mode>+(i!os$itan Co!enae 4- 9anual$ ,001This is a o!e of o"eent$ which

allows the a"atar to o"e silently without !etection. The gae contains se"eral o"eent

o!es all of which eit "aryingle"els of soun! relati"e to the spee! of o"eent.owe"er$ when the player enters > snea- mode> the a"atar2s soun! eissions are re!uce!.

/pee! anageent in Tom 'lanc(sSplinter 'ell +,00,$ Dbisoft functions in a particular

anner$ whereby the player controls the a"atar2s o"eent spee! within a threshol!.The

function is siilar to that of anaccelerator pe!al in autoobiles. )t the highest rateofo"eent the a"atar eits the highest possible soun! while o"ing$ while the opposite

is true for the lowest. The a"atar profile also alters this$ as changing the stance of the

a"ataralso changes the o"eent pattern. This eans that an a"atar o"ing in a crouch

stance+i.e. lower profileeits less soun!.

•2.1.2.1 %o#er s&stems

i!ing behin! co"er is a way of a"oi!ing !etection. n early stealth gaes$ the player

positioning thesel"es behin! a "ision'obstructing obect was enough to a"oi! !etection.

5"er tie$ taking co"er cae to !e"elop into a echanic$ which allowe! thea"atar to presshiself against these "ision'obstructing obects.These obects "ary in their shapes an!

si&es$ as long as they facilitate a!e?uate co"er fro the guar!2s sight+ Metal Gear Solid $

Konai 177.

This further !e"elope! into a echanic where!esignate!obectsacte! as co"er$ enabling the player at a push of a button to position the a"atar behin! co"er. 9o"eent o!es were also

a!!e! to these obects$ allowing players to strafe along co"ers for instance +Tom 'lanc(s

Splinter 'ell $Dbisoft ,00,.

•2.1.3 'isi(ilit&

ow a gae counicates whether the player is "isible to the guar!sor not

works!ifferently in e"erygae. This is go"erne! through rules that are applie! in thegaeworl!.The ost coon one is co"er. )llowing thea"atar to press hiself against a

wall to peek aroun! corners$ an! to crouch behin! saller obects is a coon way to

obstruct the guar!2s sight of the a"atar.


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n stealth gaes !e"elopers try to gi"e the guar!s siulate! sensory perceptions such as

"ision$ hearing an! soeties sell to create a huan like awareness. For further

information see the Artificial Intelligence section 2343#.

•2.1.3.1 %oncealment

Concealent$unlike co"er$is a way for the a"atarto blen! into thesurroun!ings$ whether it

be through caouflage + Metal Gear Solid Sna-e .ater $Konai,004$ the use ofsha!ows

for hi!ing +Tom 'lanc(s Splinter 'ell, ,00, or the use of crow!s to blen! into. + %ssassin(s'reed $$ $Dbisoft,007@hen the a"atarisconceale!$ special rules applyrestricting the

a"atar2sbeha"ior.;or e#aple in the situation in which a guar! isfacing the a"atar2sgeneral

!irection$ while incapable of sensingthe a"atar2s presence !ue to concealent$ su!!eno"eents on the part of the a"atar will cause the a"atar to be !etecte!.This ser"es as

anabstraction of how ?uickly the huan eye can react to o"eent. owe"er while this is

applicable to concealent by sha!ows an! caouflage$ su!!en o"eents will not cause!etection in the case of crow!s. Crow!s cycle constantly$ o"ing aroun! an! soeties

o"e in groups that the a"atar can o"e aong while aintaininghisconcealent. @iththe potential e#ception of crow!s$ concealent generally !oes not protect the a"atar fro

incoing gun fire or other attacks.

•2.1.) *ools

%a!gets an! firears a"ailable to the player increase their options when they face gae

challenges. Tra!itionally stealth gaes rely on ga!gets that help the player gauge the!angers they are about to encounter. These tools can range fro ra!ars that co"er entire

areas+ Metal Gear Solid $ Konai$ 177 to snake caeras that let the player peek aroun!

corners an! un!er !oors+Tom 'lanc(s Splinter 'ell, Dbisoft$,00,. %a!gets that create

!istractions are often use! to !i"ert attention fro the a"atar2s planne!!irection ofentry.These tools usually work as soun! causing !e"ices$ such as coin that be thrown which

attracts a guar!2s attention to its lan!ing spot + /itman5 'odename 01 $ (i!os nteracti"e$,001. ;irears are often presente! in these gaes as a last resort in case the a"atar

is!etecte! an! !efensi"e easure has to be taken an! soeties use! as a way to neutrali&e

guar!s stan!ing in the a"atar2spath of progression.

•2.2 "#atar %hallenges

•2.2.1 Guar!s

%uar!s are generally the ain !ynaic obstacles in a stealth centric gaeE they can patrolcertain routesor ha"e static placeents./oeties they also arch in groups + %ssassin(s

'reed $$ $,007$Dbisoft. Dpon the !etection of the a"atar they usually react with hostility$

often attacking the a"atar while alerting fellow guar!s to the a"atar2slocation. f the a"atar

anages to escape their sight$ they initiate a search for the a"atar$ using the senses an!intelligence they ha"e been gi"en.

•2.2.2 En#ironmental +a,ar!s


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These ha&ar!s e#ist as a threat that can gi"e away the a"atar2slocation to a guar!2ssenses$for

e#aple lou! flooring+Thief The Dar- 6ro7ect $


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The paper will go through!esign principles presente! by in!ustry professionals. This is

!one by e#aining stealth centric gae !esign principles an! the !esign ofartificialintelligence in "i!eogaes. 5ne can !e"elop a general perception of what stealth centric

!esign isby also e#aining the !ynaic relationship of guar! an! a"atar.


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•).1.1 Designing for stealth centric pla&

:uring %:C/an Fose in ,006$ *an!y /ith$ .

/ith !efines a coon aesthetic goal for stealth centric gaes as

[To] create the illusion of a securely guar!e! area that the player can sneak through by"irtue of le"eraging their uni?ue abilities an! tools to create an! e#ploit security flaws.

+/ith$ ,006

n cobat centric gaes the a"atar can take punishent fro their opponents until their

health gauge+ partial failure margin is !eplete! for the failure con!ition to be et$ whilestealth centric gae2s partial failure margin2s threshol! is consi!erably saller as the

failurecon!ition is the player2s inability to reain un!etecte!. +/ith$ ,006

9eeting this failure con!ition of stealth forces the player out of stealth play an!into either

fleeing or engaging in open conflict.

;igure 1 +8artial failure argin in cobat centric gaes ' +/ith$ ,006


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•).1.2

;igure , +8artial failure argin in stealth centric gaes ' +/ith$ ,006

*he importance of "rtificial ntelligence

To e#aine this further one nee!s to e#aine the a"atar2s relation to their artificial

opponents i.e. the guar!s.

/tealth poses a consi!erable proble in the !esign of artificial opponents for war gaes. n

a gae with no stealth$ the )'!ri"en opponent has access to the coplete state of the gaeworl!E to inclu!e stealth$ you[the gae !esigner] ust restrict the opponent2s knowle!ge$

liit its attention$ lea"e it ignorant of whole regions of the gae worl!. You !eci!e what

the ) opponent !oes an! !oesn2t know an! !efine what steps it takes if any to gain furtherinforation. +)!as$ *ollings$ ,00-

@hile this ?uote originally talks about gaes in the real'tie strategy genre$ it is still true

for stealth centric gaes.

The guar!s are !ri"en by an )rtificial ntelligence +) an! the ) ust gather inforationin or!er to fin! the possible whereabouts of the a"atar. %enerallythe guar!s aren2t

constantly searching for the a"atar as they often are obli"ious to the a"atar2s e#istence.owe"er to be able to react to the a"atar2spresence these guar!s nee! eans to gather

inforation about the possible presence of a threat. The eans coes in the for ofartificial senses.

n the Gamasturafeature >Buil!ing an ) /ensory /yste (#aining The :esign of Thief

The Dar- 6ro7ect >$ To


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The ter >senses> in gae !e"elopent is a useful etaphor for un!erstan!ing$ !esigning$

an! !iscussing that part of the ) that gathers inforation about ites of interest in thesiulate! en"ironent of the gae. Gon'player characters "isually presente! as huans$

anials$ or creatures with eyes an! ears in a realistic three'!iensional space len!

thesel"es well to the etaphor. +


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n ore cople# gaes$ you ay nee! to account for the player or other entities being

hi!!en by soe sort of co"er. ;or this type of gae$ you ay nee! to perfor a ray trace+soeties referre! to as a ray cast to see whether soething has blocke! the potential

target. ) ray trace is a atheatical way of checking if a ray intersects anything$ starting

fro a single point an! going in a set !irection.+Kehoe$ ,007

Kehoe also goes into the ipleentation of hearing an! selling senses

)t first blush$ it ay see like soun! is no !ifferent than sight. f you can see an entity$certainly you can hear it$ too. t2s true that if your agent [guar!] has spotte! an entity$ the

agent can acti"ely !etect anything that entity !oes until it is no longer in sight. owe"er$

a!!ing an e#tra le"el of hearing to your agents can help ake sight work ore effecti"ely.Tracking the noise that entities ake as a le"el of perception is key to any stealth'base!

gae. +Kehoe$ ,007

)!!ing the sense of sell to a gae is relati"ely easy %i"e each entity in the gae a

!istinct sell nuber an! strength. The strength of the sell !eterines two factors thera!ius of the sell an! the si&e of the scent trail left behin!. )cti"e player entities often

keep track of their last few positions for a nuber of reasons [.....]. 5ne reason coul! be to

help entities with sell. )s the player entity [a"atar] up!ates the trail$ the strength of thesell !iinishes as the trail grows >col!.> @hen an agent [guar!] with sell is up!ate!$ it

nee!s to check for sells like it woul! check for soun! [to check the sell] ra!ius an!

check [if] walls [are blocking the guar!s sell ra!ius]. +Kehoe$ ,007

/cent trails for the guar!s fro thea"atar$allowthe guar!sa ore realistic reaction to thea"atar2s !isappearance.This in!icates which !irection the guar! shoul! start searching for

the a"atar2shi!eout position$ or alternati"ely their !irection of escape35"er the course of

tie while theguar! is searching the area$ acti"ely looking for the a"atar$the trail can startweakening$ allowing the guar! to transition ore naturally to his i!le patrol pattern an!

o"e back to his post.

(?uipping a guar!2s ) with senses such as "ision$ hearing an! sell lea!s to a gaesyste in which the guar!s are capable of reacting to thea"atar2sactions in the en"ironent.

*an!y /ith callsthese actions e*pressions perfore! by the player. These

e#pressionsarewhat ake the a"atarore or less !etectable by the guar!2s )'controlle!

senses$ creating a relationship between player an! ) which results in stealth play+/ith$,00,.


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;igure 4 +/tealth ' +/ith$ ,00,

/ith e#plains this using the following Henn !iagra +see$ fig.4

The a"atar hasgoals to fulfill an!useshis o"eent e#pressions+i.e. actions to reach these

obecti"es. 5nce the obecti"e is fulfille! the a"atarhasattaine! success+in stealth play.owe"er$ using these o"eent e#pressions$affects their !etectability either by pro!ucing

soun! or increasing their "isibility to the guar!s. This happens in relation to

thea"atar2slocationin theen"ironent the a"atar is trea!ing !uring play.

:epen!ingon thea"atar2sbeha"iorguar!s has to use theirsenses to !etect an! fin! theappropriate reaction to the a"atar2sactions3This is !one through the ) coponent of a

guar! where they engage in !ecision aking.

•).1.3 " Decision making

;inite'state achines are a etho! of o!eling software2s systes relationships an!

operations. :esire! beha"iors ten! to be represente! by no!es which are interlinke! by

arrows to !isplay their relationships. These relationships ay range fro progressi"e step by step proce!ures$ to ore a!"ance! interconnecte! series of operations.


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The core concept behin! ) is !ecision aking. To e#ecute these choices$ the intelligent

syste nee!s to be able to affect the entities using the ) syste. +Kehoe$ ,007

) finite;state machine can for e#aple be use! as a fraework to !eterine which state of beha"ior aguar! will be in. @hen certain criteria ha"e been et$ a new state of beha"ior

can be entere!.

) >state>can represent physical con!itions that the entity is in$ or it can represent eotional

states that the entity can e#hibit. n this e#aple$ eotional states are nothing like a true)2s eotional states but pre!eterine! beha"ior o!els that fit into the conte#t of the

gae.+Kehoe$ ,007

These statesare triggere! by the a"atar2se#pressions$ for e#aple the a"atarcausing a lou!

noise while trea!ingon a lou! surface.

;igure I +) finite'state achine ' Beha"ioral states illustrate! by no!es which are oin byarrows e#planing possible transtions between states. ' +Kehoe$,007

Kehoe uses the following figure to e#plain the states aguar! can take on in >a gae withstealth eleents>+Kehoe$ ,007

e continues to e#plain each state in the figure

!le /

n this state$ the entity is passi"ely stan!ing aroun! or walking along a set path. 8erceptions

are low. 8layer soun!s are not often checke! for. 5nly if this entity is attacke! or >sees> a player !irectly in front of it will its state change to a higher le"el of awareness.2+Kehoe$

,007


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"ware /

This entity is acti"ely searching for intru!ers. t checks often for the soun!s of the player

an! sees farther an! wi!er than an i!le entity. This entity will o"e to the ntrigue! state ifit notices soething out of place +soething to check for$ such as open !oors$ unconscious

bo!ies$ or spent bullet casings.> +Kehoe$ ,007

ntrigue! /

This entity is aware that soething is up. To !eonstrate this beha"ior$ the entity willaban!on its noral post or path an! o"e to areas of interest$ such as the aforeentione!

open !oors or bo!ies. f a player is seen$ the entity goes to the )lert state.> +Kehoe$ ,007

"lert /

n this state$ the entity has becoe aware of the player an! will go through the actions of

hunting !own the player o"ing into range of attack$ alerting fellow guar!s$ soun!ingalars$ an! fin!ing co"er. @hen the entity is within range of the eney$ it switches to the

)ggressi"e state.> +Kehoe$ ,007

"ggressi#e /

This is the state where the eney has engage! in cobat with the player. The entity attacksthe player when it can an! seeks co"er between roun!s of attack +base! on attack cool'

!owns or reloa!ing. The entity only lea"es this state if the eney is kille! +return to

noral$ if the eney o"es out of firing range +go back to the )lert stage$ or if the entity!ies +go to the :ea! state. f the entity becoes low on health$ it ay switch to the ;leeing

state$ !epen!ing on the courage of the specific entity.> +Kehoe$ ,007

0leeing /

n this state$ the entity tries to run fro cobat. :epen!ing on the gae$ there ay be a

secon!ary goal of fin!ing health or lea"ing the play area. @hen the entity fin!s health$ itay return to the )lert state an! resue cobat. )n entity that >lea"es> is erely !elete!.2

+Kehoe$ ,007

Dea! /

n soe gaes$ the state of !eath ay not be copletely i!le. :eath or !ying can ha"e theentity >cry out$> alerting nearby entities$ or go into a knocke!'out state$ where it can later

be re"i"e! by a e!ic +an! returne! to a state of )lert.2 +Kehoe$ ,007

The fiel! of ) is a cople# area of research. ) for gaes takes on !ifferent fors

!epen!ing on the nee!s of the gae2s !esign$ ranging fro siple sets of rules forcoputer'controlle! entities to ore a!"ance! a!apti"e systes. )pplying ) concepts to


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gaes is a necessary way to increase the belie"ability of the "irtual characters create! in

electronic entertainent$ but it is not an ipossible challenge. +Kehoe$ ,007

The ) state achine of the guar! pro"i!es the possibility for the guar! to a!opt !ifferent patterns of beha"iorin the occurrence of !ifferent e"entsE whether itbe the !etection of the

a"atar or noticing suspicious acti"ity in their "icinity. This allows for a certain !ynaic toeerge that eets the aesthetic goal +accor!ing to 9:) for stealth centric play$ presente!at the start of this paper.

the player ust o"e to succee!$ but o"ing akes the !etectable$ an! the ) senses

pick up on that$ possibly e"entually lea!ing to the failure state.+/ith$ ,00,

;igure 6 +Basic relationship re?uireent ' +/ith$ ,00,

•).1.) #erall le#el !esign consi!erations

n theGamasutra article >:esigning Better


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gae spaces that$ !ue to perception of the space an! other factors$ trigger !ifferent huan

eotions.

The following ters are !efinitions for spaces chosen for their rele"ance to this paper.

•

Prospect Space >8rospect /pace !escribes a spatial con!ition that is wi!e open$within which the occupant is e#pose! to potential eneies.>+Totten$ ,011

• efuge Space >*efuges are places like ca"es an! tree co"ere! areas where early

huans coul! look out into the 8rospect spaces of wil!erness an! e"aluate potential

threats.>+Totten$ ,011

Totten uses those two spaces to argue that players can ake use of a *efuge /paceto lookfor a /econ!ary *efuge /pacean! o"ebetween these spaces. e then writes about how

this concept can be utili&e! in stealth centric gaes by creating se?uences where players

o"es fro refuge to prospect to secondar refuge in a repeating pattern to coplywith

theaesthetic of stealth+,011.

woul! argue that 9%/2s [9etal %ear /oli! series] le"els are actually base! upon the

*efuge'8rospect'/econ!ary *efuge se?uence$ as the stealth gaeplay re?uires you to o"e

fro hi!ing place to hi!ing place. This type of gaeplay changes un!ane en"ironentaleleents like corners an! lockers into safe places !ifferentiate! fro the 8rospect areas of

the le"el with guar!s an! caeras. +Totten$ ,011

Totten also entions the concept of Sha!ow Spacewhich>creates the perception that one

roo is actually two areas within the /ha!ow an! areas in the light.> *eferring toTom'lanc(s Splinter 'ell +Dbisoft$ ,00, for instance$which akes use of sha!ows as a eans

of concealent$ creating a secon! space within the roo which functions as a one'wayirror. This eans that onecan "iew the content of the outsi!e roo fro within thesha!owE howe"er an ) cannot see the contents of the sha!ow space while "iewing fro

the outsi!e.

There is a !ifference between !esigning le"els for cobat centric an! stealth centric gaes.

n cobat centric gaes it is "ali! to create challenging roos an! assue all players wille#perience soe !egree of failure. owe"er in a stealth centric gae$ !esigners can2t

assue the player will fail. nstea! the gae shoul! pro"i!e the eans for the player to

e#perience little to no failure +/ith$ ,006.

This eans stealth le"els shoul! refrain fro ha"ing challenges where the security actuallyis ipenetrable$ unless it is an area the player is not suppose! to ha"e access to. This

becoes a balancing act where if security is too tight$ the player will be incapable$ howe"er

if there are too any eans that support the player$ the gae will cease to be stealthy+/ith$ ,006.

*an!y /ith suggests that ha"ing open'en!e! le"els allows the player ore fle#ibility$

ipro"isation an! player e#pression !uring play sessions.


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when theyperit ore paths to be taken when creeping through areas. This akes the le"el

ore of a playgroun! an! akes the gae less of an authore! e#perience for the player.owe"er the larger nuber of "ali!routes the player can choose to breach security$ the

ore obstacles that ha"e to be ipleente! in or!er to balance the player e#perience

+/ith$ ,006.

;igure - +5pen'en!e! le"el structure ' +/ith$ ,006 note iage has been e!ite! for the

purpose of this paper.

The following figure +fig.- shows a roo where it is possible for the player to take

ultiple paths in or!er to pass through. The roo contains two guar!s$ a patch of lou!

flooring an! two torches that light up certain areas of the roo. These are the ainchallenges the player has to !eal with in this roo./ha!ows are howe"er present$ which the

a"atar can use for concealent. The challenges work to repel the player away$ while

hefin!shisway aroun! the en"ironent an! the sha!ow ser"es as eans to a"oi!


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!etection.owe"er which paths are apparent to the player is "ery !epen!ent on how the

en"ironent iscounicate!through the caera o!el use! in the gae.

•).2 Perspecti#es %amera mo!els an! pla&er o#er#iew

The perspecti"e a gae is presente! fro affects the way the gae is going to be playe!. t

!eci!es how all inforation that is going to be transitte! to the player is presente! an!

possibly interprete!. The following sections will !iscuss how caera o!els an! userinterfaces are applie! to stealth centric gaes$ in or!er to for an o"er"iew of the

situations the player is going to work with while they a!"ance fro one challenge to

another +)!as$ ,00-$pp. ,41',4.

•).2.1.1 %amera $o!els

This paper uses the following e#planation of the wor! caera o!el

f a gae inclu!es a siulate! physical space$ or game +orld $ then it alost certainly uses

graphics to !isplay that space to the player. The user interface ust !isplay the space fro

a particular angle or point of "iew. :esigners usually iagine that a hypothetical caera is pointe! at the "irtual space$ creating the iage that the player sees. The syste that

controls the beha"ior of this iaginary caera is calle! the camera model . +)!as$

*ollings$ ,007

•).2.1.2 *hir! person perspecti#e

The thir! person perspecti"e o!el allows the player to see his a"atar2s physical for inrelation to the gae space$ while playing. There are two coon "ariations present in

stealth centric gaes. 5ne is a so calle! the top;do+n "iew. This "ariation places the

caera far abo"e the a"atar allowing the player to see a "ast part of the en"ironent at thesae tie. The caera in soe gaes also follows the a"atar along the en"ironent.

+9etal %ear /oli!$ Konai$ 177 ;ro a !esign stan!point this caera syste allows the

player to ?uickly get an o"er"iew of the en"ironent the a"atar is tra"ersing. ;or e#apleEthe player can easily obser"e the patrol patterns carrie! out by guar!s in relation to

thesel"es as an obect within the gae space +)!as$ *ollings$ pp.,I6.

ow far the player can see is !epen!ent on the caera2s !istance fro the player$ generally$

the further away$ the ore one can see. This can also ean that the perspecti"e liits the player2s ability to anticipate challenges outsi!e the caera2s fiel! of "iew. Thislea!s to the

possibility ofthe player feeling unfairly treate! if a guar! is able to attack fro a !istance

beyon! the top'!own caera2s "iew +)!as$ *ollings$ pp.,I6.

The secon! "ariant is calle! a D third;person "iew$ an! is essentially a caera systewherethe caera rotates aroun! the player a"atar$ using the player a"atar as a center of

gra"ity. +To Clancy2s /plinter Cell$ Dbisoft$ ,00, The caera2s !efault position is usually


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soewhat o"er the a"atar$ in soe instances they are set fro an o"er'the'shoul!er'"iew

allowing the player to "iew what is in front of thea"atar. This o!el also allows the playerto see a little of their near surroun!ings. n this caera o!el the player often controls the

rotation of the caera !eci!ing which angle is the ost appropriate at any gi"en tie

!uring play +)!as$ *ollings$ pp.4I-.

•).2.1.3 0irst person perspecti#e

n this caera o!el the caera is place! in the player a"atar2s hea!$ so as to gi"e theillusion that the player is seeing the worl! fro the a"atar2s >eyes>. This o!el gi"es the

player the ability to see what is happening ahea!$ allowing the gae to ha"e threats such as

snipers in their le"els without the player feeling at a !isa!"antage. )s the player turns thecaera as if they were the a"atar2s bo!y$ the player can focus on what they think is

iportant. @hile it can see realistic this "iew only lets the player see things in the

!irection the a"atar is facing +)!as$ *ollings$ pp.,4,$ 4I6$ ,00-.

n a first'person gae$ the player2s sense of bo!y is weak$ an! the player seen by anopponent they !o not see often feels cheate!. +f the caera o"es 'especially if it ups su!!enly'the player

will becoe !isoriente! an! is likely to ake istakes.> +)!as$ *ollings$ pp.4I$ ,00-

•).2.3 $ixing an! matching camera mo!els

t is coon for stealth centric gaes to switch between ultiple caera o!els. This can

be !one in or!er to copensate for the ain caera o!el2s liitations. 5ne coon

e#aple is the use of a 3: thir! person caera o!el for na"igation aroun! en"ironents$while allowing the player to switch into a first person caera o!el for precision aiing

with firears + Metal Gear Solid # Sons of Li&ert$ Konai$ ,001 or as a way ofobser"ing what is happening further ahea!$ which can allow the player to gauge threats

early on + Metal Gear Solid $ Konai$ 177.

5ther e#aples in"ol"e switching fro first to thir! person caera o!el when the

a"ataris presse! against the wall for co"er+ Deus .* /uman


20/26

,011. This can allow the player to peekaroun! the e!ges of a wall without e#posing

thesel"es to threats. There are instances where gaes switch fro a thir! person caerao!el to a conte#t sensiti"e caera o!el. This ay happen for e#aple when the player

enters a narrow space where a 3: rotating caera will not function well an! can potentially

get stuck behin! a wall+ %ssassin(s 'reed $ Dbisoft$ ,00-.

•).2.) "c4uiring information (e&on! the camera mo!el

)ccor!ing to the bookE ;un!aentals 5f %ae :esign$ the challenge type of stealth centric

gaes is >[to]a"oi! being seen>.+)!as$ *ollings$ ,00- This eans that in or!er for the

player to a"oi! being spotte! by guar!s$ the player plans an! obser"es his surroun!ings before attepting to o"e through an area to another. nforation gathering is

re?uire!before the player takes action. The caera o!els presente! abo"e allow the player

to coprehen! ost of the inforation nee!e! for the player2s progression. owe"er whenthe player has to o"e aroun! a blin! corner$ the potential threats are not ob"iously

e#pose! to the player. This gap of inforation can be ree!ie! by pro"i!ing the player

with tools$ to help the gain inforation fro areas they cannot !irectly obser"e fro acofortable !istance.

) close! !oor can represent a conceale! area for the player that they e"entually ha"e to

enter. 9any echanics ha"e been !esigne! to a!!ress this$ all with ore or less the sae

resultE being able to see what is happening on the other si!e$ by letting the player peekthrough a key hole$ gi"ing the player liite! "isibility of the roo ahea! + /itman # Silent

%ssassin$ 5$,00,.

5ther solutions can be slipping in a caera un!er the !oor$ allowing the player to look in

fro a low profile an! a!ust the caera2s orientation to re"eal ore of the surroun!ings

+Tom 'lanc(s Splinter 'ell,Dbisoft$,00,. There are tools such as goggles that allow the player to see through opa?ue obects or !etect heat signatures fro guar!s +Tom 'lanc(s

Splinter 'ell $ Dbisoft$ ,00,.

5n soe occasions the caera echanics ha"e e"ol"e! into a sticky'caera +sticks towalls that can be launche! into high risk !etection areas$ where the player has little to no

o"er"iew before entering.

)s stealth gaes ten! to ha"e ore open le"els$ this becoes iportant. 9ini'aps can be

use! to copensate for the caera o!el2s liitations in three !iensional spaces$ as it can be !ifficult for a caera o!el to a!!ress all the inforation coing fro all three

!iensions at once.

•5. Discussion

•5.1 *he " guar! an! pla&er relation


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The patrolling guar! e#ists to counter the a"atar2s ability to o"e freely through the gae

space.Dsing their senses the guar!s are capable of co"ering territory !irectly through their"ision an! in!irectly through other senses such as hearing an! selling. Thisis a general

re?uireent for stealth centric !esign to work.

) practical solution to aking an e#cee!ingly static stealth centric space is to populate thespace in ?uestion with guar!s. owe"er it is iportant not to create a !isproportionate le"elof challenge outsi!e of the play style2s aesthetic abition.

%uar!s ha"e a "ariety of states that reflect their localgae space status$ at any gi"en tie.

These are built purely aroun! the a"atar2s actions. These actions are interprete! through

sensory systes in the guar!s$ resulting in action causation.

) gae sensory syste ust be !esigne! in a way that is subser"ient to the gae !esignan! efficient in ipleentation. The senses nee! only be as sophisticate! as is nee!e! to be

entertaining an! robust. The result of their work ust be percei"able an! un!erstan!able by

the player.+


22/26

;igure +9etho!s of pacing ' +/ith$ ,006 note iage has been e!ite! for the purpose of

this paper.

•5.3 e&on! sha!ow space

The concept of sha!ow space can take on !ifferent fors beyon! the concept of a static

sha!ow where the player can ha"e an outlook$ without being in !anger of !etection. n

%ssassin(s creed $$ +Dbisoft$ ,007crow!sare use! by thea"atarto blen! in aongci"ilians.This attribute essentially akes crow!sact as a obile sha!ow space. The use of

caouflage in Metal Gear Solid Sna-e .ater +Koia 8ro!uctions$ ,004 can also be seen

as a for of sha!ow space$ where the a"atarcan use the aority of the en"ironentaslocations to a"oi! !etection. n short$ sha!ow space pro"i!es concealent which can take

on !ifferent fors. The a"atarcan be partially conceale! fro the ) as well. Both Tom

'lanc(s Splinter 'ell +Dbisoft$ ,00, an! Metal Gear Solid Sna-e .ater +Koia8ro!uction$ ,004 ha"e anin!icator in placethat counicateto which !egree the a"atar isconceale! fro the guar!s.

•5.) nterconnecting challenges

There sees to be ageneral un!erstan!ing thatplayers nee!to plan e"ery encounter byobser"ing what is ahea! of the. owe"er creating open'en!e! le"el structures ay also

cause any of these challenges to interconnect. ;or e#aple$ in fig.- reaching the i!!le

of the roo !oes not only ean the possibility of !ealing with lou! flooring as well as

re"ealing light sources. )!!itionally the two guar!s patrolling are also a threat as theysur"ey the area.This eans that the player is +!epen!ing on the patrol pattern in constant

!anger of !etection fro two si!es. These challenges can$ howe"er$ be a"oi!e! by using the

sha!owy si!e corri!or$ by !oing sothe players a"oi! the interconnecting challenges i.e. theintertwine! guar!s$ lou! flooring an! re"ealing lights.

•6. %onclusion


23/26

The following list outlines what this paper has coe to fin! are the essential core

coponents of stealth centric gaes

• $o#ementin stealth centric gaes the purpose of o"eent goes beyon! the

a"atar2s na"igation of the gae space. 9ultiple o"eent o!es are often

ipleente! allowing the player a higher !egree of control o"er the a"atar2s!etectability.

• %o#er or concealment to counter "isibility the gae nee!s toha"e an en"ironent

that pro"i!es the a"atar with the eans for hi!ing$ whether be it crow!s in the citystreet to blen! aong or a crate to hi!e behin!.

• Guar!s or Securit& measures These are the ain a!"ersaries the a"atar has to

!eal withE they nee! to be present enough for the area to see securely guar!e!$ but

not to the point where security is ipossible to breach.

• "larm stateis the failure con!ition of stealth play an! soeties the gae itself$signaling the nee! for the player to !eci!e whether to flee or fight.

• asic sensor& s&stem as the a!"ersaries of these gaes !o not ha"e access to the

coplete state of the gae$ they nee! to ha"e soe eans of !etecting the a"atar2s

presence through at least binary !etection using "ision$ hearing or selling.

• "estheticall& !eman!ing le#els The le"els in these gaes ha"e to be constructe!

with all of the entione! abo"e in in!$ abi!ing by the aesthetics of stealth which

is>[To] create the illusion of a securely guar!e! area that the player can sneak

through by "irtue of le"eraging their uni?ue abilities an! tools to create an! e#ploit

security flaws> +/ith$ ,006.

@ith this$ one can plausibly !e"elop a stealth centric gae that can ake use of the

aesthetic that !efinesthis type of gaes. ;or e#aple one can apply the aesthetic of stealth

to a gae where the player takes control of a car$ a"oi!ing spee! caeras an! police patrols. This is significant because it shows that the aesthetic of stealth can take on a "ariety

of settings an! thees$ as long as theplayers thesel"es act as hi!!en threats to the current

alar state$ thereby a"oi!ing !etection.

These liste! coponents howe"er$ are only a base set o"er which all other !iscusse!attributes of stealth can be a!!e! to wi!en the partial failure argin in play$ thus e#pan!ing

the grey &one where the player ay operate while a!hering to the aesthetic of stealthcentris.

•6.1


24/26

0urther esearch

%oing beyon! this paper2s conclusions$ it is possible for us to further our insights intostealth gaes. Through e#aining further other stealth centric gaes we coul! coe to

learn ore about how these gaes are playe!.

)s these gaes ten! to be open'en!e!$ allowing the player to use ultiple approaches to

progress through challenges. This also eans that there is boun! to be a "ariety ofapplicable play styles to stealth centric gaes. The potential of i!entification of these play

styles will be e#plore! in y future work through analysis of conteporary titles release!

within a set of years. By !oing so$ one can also reach a reliable perception of the currentstate of this type of gaes$ e#pan!ing the scope of possibilities for future !e"elopent of

stealth centric gaes.

Glossar&)"atar >) fictional character in a gae with who the player i!entifies as the

personification of herself with in the gae worl!. The character nee! not be huanE it ay

e"en be a "ehicle.> +)!as$ *ollings glossary %1$ ,00-

%ae worl! >)n iaginary uni"erse in which the e"ents of the gae takes place. 9ostcoputer gae worl!s are siulate! two' an! three'!iensional spaces containing

characters an! obects.> +)!as$ *ollings glossary %I$ ,00-

%ae space The space in which the player interacts with other actors or entities !irectly.

/tealth The thee! aesthetic goal set forth by a !esigner$ for a player to achie"e within a

gae spaceE to act an! approach challenges in a co"ert anner.

/neak The proce!ure of o"eent to the conte#t of /tealthE to o"e in a ?uiet an!

cautious fashion.

)"atar profile This refers to the a"atar2s current "isual copositionE be it respecti"e of

stance$ shape or color.

9ini'aps >) sall$ !ynaically up!ate! ap of the game +orld $ usually !isplaye! in thecorner of the screen in the primar gamepla mode$ for ?uick reference. )lso soeties

calle! ra!ar screen> +)!as$ *ollings$ glossary %-$ ,00-

(ntity >) !atu or collection of !ata that !escribes soe obects$ character$ ?uantity$ or

state of affairs> +)!as$ *ollings$ glossary %4$ ,00-


25/26

Boss encounter >) large an! particularly !ifficult challenge that ust be o"ercoe$

typically the last one re?uire! in or!er to coplete a level of a gae> +)!as$ *ollings$glossary %,$ ,00-

i(liograph&)!as$ (. +,007$ Fuly 07. >The :esigner2s Gotebook /orting 5ut the %enre 9u!!le>.

*etrie"e! /epteber 16$ ,01,$ fro Gamasutra3comhttpJJgaasutra.coJ"iewJfeatureJ13,463Jthe!esignersnotebooksorting.phpAprintL1

nteracti"e$ (. +8ublisher. +,001. /itman5 'odename 01 [Hi!eo %ae].

Kehoe$ :. +,007$ Fune ,0. Designing %rtificial $ntelligence for Games 96art 4:. *etrie"e!

Fune 1,$ ,01,$ fro software.intel.co httpJJsoftware.intel.coJen'usJarticlesJ!esigning'artificial'intelligence'for'gaes'part'1J

Konai +8ublisher. +17-. Metal Gear [Hi!eo %ae].

Konai +8ublisher. +177. Metal Gear Solid [Hi!eo %ae].

Konai +8ublisher. +,00,. Metal Gear Solid # Sons of Li&ert [Hi!eo %ae].

Buil!ing an ) /ensory /yste (#aining The :esign of

Thief The :ark 8roect>. *etrie"e! 9ay ,0$ ,01,$ fro Gamasutra3comhttpJJwww.gaasutra.coJ"iewJfeatureJ,Jbuil!inganaisensorysyste.phpA

printL1

8ro!uctions$ K. +8ublisher. +,004. Metal Gear Solid Sna-e .ater [Hi!eo %ae].

*obin unicke$ 9. . Chichester Fohn

@iley O /ons$ The ;un!eentals 5f %ae :esgin>3 Gew Fersey 8earson

8rentice all.

/ith$ *. +,00,. >:esign ;un!aentals of /tealth %aeplay in the Thief series>. Game

Developers 'onference +pp. 1'I0. /an Fose ionstor.co.

/ith$ *. +,006. >


26/26

/tu!ios$ :esigning Better ;inite /tate 9achine. *etrie"e!> 04 ,6$ ,013$ fro 8' State

Universit httpJJwww4.ncsu.e!uJM!rwrigh3J!ocsJcoursesJcsc,16Jfs'notes.p!f

*eturn to the web "ersion of this article

Copyright P ,014 DB9 Tech@eb
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examining the essentials of stealth game design

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