Topics History of RPGs Problems with large worlds Problems with
faction reputations Problems with scripted AI Summary Problems with
what games teach us (if there is time)
Slide 3
History Stem from role plays such as improv comedy, war re-
enactments Migrated to a table top game, such as Dungeons and
Dragons obligatory video http://www.youtube.com/watch?v=XHdXG2gV01k
http://www.youtube.com/watch?v=XHdXG2gV01k With advent of early
computing, the games moved into the computer/console world, but
lost the multiplayer element With the internet, the social aspect
has returned, but the dungeon master is nowhere to be found
Slide 4
Early Examples Text based games on Unix systems Evolved to
projects like Ultima, with richer graphics and interface
improvements RPGs as we know them borrow a lot from Ultima III and
Dungeon Master (both 1987)
Slide 5
Common Elements Story driven gameplay Character development and
customization Multiple character party Top down view Combat system
which abstracts concrete details
Slide 6
Combat Systems Turn Based Most console rpgs Some variation in
what can be done in a turn (Tactics) Ex: Final Fantasy Real Time
Most computer rpgs Still abstract away the skill of combat leave it
to strategy Some variants, especially in consoles (Secret of Mana,
Mario RPG)
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Expansive Worlds Early games not small due to lack of
creativity just resources Cartridge capacity Simplified AI Current
games are expected to be large and behave realistic, but is this an
option?
Slide 8
You Must Gather Your Party Before Venturing Fourth CPU time
limited AI focused on master area Players must stay together
Slide 9
Taking a Page from the GPU Relate processing effort to the
distance away from player
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Continuous Distance Function CPU time directly proportional to
the distance to the nearest player character Mathematically elegant
Not too efficient
Slide 11
Discrete Level of Detail Function in NWN LODClassification
1Player Characters (your party) 2Creatures fighting or interacting
with a PC 3Creatures within 50 meters of PC 4Creatures in the same
large scale area as the PC 5Creatures in areas without a PC
Slide 12
Example
Slide 13
Splitting the CPU CPU TimeLevel of Detail 60%LOD1: Player
Characters 24%LOD2: Creatures interacting with PCs 10%LOD3:
Creatures in proximity of PCs 4%LOD4: Creatures in an area of a PC
2%LOD5: Creatures not in an area with a PC
Slide 14
Trimming the Fat LOD1, 2, 3 perform full pathfinding LOD4 hops
tile to tile LOD5 teleports to destination Do we even need them to
walk? Perform damage calculations?
Slide 15
Reputations in MMOGs Used to simulate intelligent factions Can
be increased decreased, with a ripple effect Provide non-linear
gameply (have to choose sides) Global and instant is this
realistic?
Slide 16
Example
Slide 17
Typical Event Subject GroupPlayer VerbDidViolenceTo Object
GroupBandit Object IndividualJoe Magnitude75 (Killed)
Where50,20,138 (in front of saloon) WhenHigh Noon
TemplateKilledBanditTemplate Reference CountKnown by 11 NPCs
Reputation EffectsBandits hate player more Lawmen like player more
Farmers like player more
Slide 18
Where to put the events? Could assign a copy to each NPC that
was present Waste of space Solution keep a master list Only keep
most severe events Delete events no longer referenced Have NPCs
forget over time
Slide 19
Working with Events After an action, an EventAnnouncer adds the
event to the master list The announcer continues to broadcast the
event to NPCs in a certain radius NPCs may share events with each
other, provided they are on speaking terms
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Updating Events Each NPC tries to find if the event is new to
them We may already know of a more serious event, so we already
have enough hate We may need to replace less serious events with
this one An event can be committed by unknown; should we remember
it?
Slide 21
Declarative AI Design Currently Imperative design is most
common It allows things to be scripted precisely, like a movie
scene Behavior is brittle outside of intended environment This
takes time/money to develop, and games are growing in size
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Imperative Design Well known and used in the community Allows
for quick, simple scripts to address issues, much like band-aids.
Fits well with the typical scenario of a map with objects and
actions
Slide 23
Another Reason: Player Interaction with AI Players discovering
new ways of interacting with the NPCs or world systems Players
interacting with other players via markets and trading Players
creating new objects or services in the world via modding or UI
add-ons Players pushing the world rules system, including its
AI
Slide 24
Solution: Goals Dictate NPC behavior based on constraints and
goals Constraints are the intrinsic rules of the game / map Goals
are typical behaviors that we previously had to solve ourselves and
hardcode the solution for the NPC
Slide 25
Example I want the assassin to leap out of the shadows from
here and run over there, then to twist left and fire his gun. VS
Sun-tzu said in The Art of War that there are six types of ground:
accessible, entangling, stalemated, narrow, steep, and expansive.
If the enemy is unprepared on entangling ground, advance and defeat
him.
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Usage in Age of Empires Building rules Resource gathering rules
Attack rules Winning rules Diplomatic rules Research rules
Evacuation rules
Benefits Allows a uniform approach to dictating behavior (no
more band aids) Allows for more flexibility when it comes to
learning algorithms Will react to player behaviors not envisioned
by the programmer Development time not linearly related to the size
of the game
Slide 29
Summary Full Circle Games well defined before computers Porting
to computers removed social aspect The internet brought it back All
thats left is to improve the dungeon master.
Slide 30
Bonus What Games Really Teach Chess Appears to be about war, it
has knights, castles etc Really about controlling space, predicting
opponent GTA Appears to be about shooting pedestrians and cops
Really about exploration and freedom WoW exploration and role
playing?
http://www.gamasutra.com/features/20060222/sirlin_01.shtml
Slide 31
What WoW Really Teaches Investing a lot of time into something
is more valuable than actual skill You deserve it more if you put
in more time Very relevant to the Honor System Completely opposite
in real life Group is better than solo Much better rewards for
performing mundane tasks along with 39 other people than individual
skill Prevents exploration and exploitation of engine with soft
rules (Larry Lessig disapproves -.-) Uses TOS to ban behaviors
otherwise allowable in game As Comp Scis, we know this is never an
option in the real world
http://www.gamasutra.com/features/20060222/sirlin_01.shtml