<s>
Call	B-Application
of	I-Application
Duty	I-Application
is	O
a	O
2003	O
first-person	O
shooter	O
game	O
developed	O
by	O
Infinity	O
Ward	O
and	O
published	O
by	O
Activision	O
.	O
</s>
<s>
It	O
is	O
the	O
first	O
ever	O
Installment	O
in	O
the	O
Call	B-Application
of	I-Application
Duty	I-Application
franchise	O
,	O
released	O
on	O
October	O
29	O
,	O
2003	O
,	O
for	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
The	O
game	O
simulates	O
infantry	B-Protocol
and	O
combined	B-Protocol
arms	I-Protocol
warfare	O
of	O
World	O
War	O
II	O
using	O
a	O
modified	O
version	O
of	O
the	O
id	B-Application
Tech	I-Application
3	I-Application
engine	O
.	O
</s>
<s>
Much	O
of	O
its	O
theme	O
and	O
gameplay	O
is	O
similar	O
to	O
the	O
Medal	O
of	O
Honor	O
series	O
;	O
however	O
,	O
Call	B-Application
of	I-Application
Duty	I-Application
showcases	O
multiple	O
viewpoints	O
staged	O
in	O
the	O
American	O
,	O
British	O
,	O
and	O
Soviet	O
theaters	O
of	O
World	O
War	O
II	O
.	O
</s>
<s>
The	O
game	O
introduced	O
a	O
new	O
take	O
on	O
AI-controlled	O
allies	O
who	O
support	O
the	O
player	O
during	O
missions	O
and	O
react	O
to	O
situational	O
changes	O
during	O
gameplay	O
.	O
</s>
<s>
Much	O
of	O
Infinity	O
Ward	O
's	O
development	O
team	O
consisted	O
of	O
members	O
who	O
helped	O
develop	O
Medal	B-Application
of	I-Application
Honor	I-Application
:	I-Application
Allied	I-Application
Assault	I-Application
.	O
</s>
<s>
In	O
September	O
2004	O
,	O
an	O
expansion	O
pack	O
called	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
United	I-Application
Offensive	I-Application
,	O
which	O
was	O
produced	O
by	O
Activision	O
and	O
developed	O
by	O
Gray	O
Matter	O
Studios	O
and	O
Pi	O
Studios	O
,	O
was	O
released	O
.	O
</s>
<s>
At	O
the	O
same	O
time	O
the	O
N-Gage	B-Device
Version	O
got	O
an	O
Arena	O
Pack	O
with	O
3	O
new	O
Levels	O
.	O
</s>
<s>
An	O
enhanced	O
port	O
of	O
Call	B-Application
of	I-Application
Duty	I-Application
for	O
the	O
PlayStation	B-Operating_System
3	I-Operating_System
and	O
Xbox	B-Operating_System
360	I-Operating_System
,	O
titled	O
Call	B-Application
of	I-Application
Duty	I-Application
Classic	I-Application
,	O
developed	O
by	O
Aspyr	O
,	O
was	O
released	O
worldwide	O
in	O
November	O
2009	O
with	O
the	O
release	O
of	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
Modern	I-Application
Warfare	I-Application
2	I-Application
,	O
being	O
available	O
via	O
redemption	O
codes	O
included	O
with	O
the	O
"	O
Hardened	O
"	O
and	O
"	O
Prestige	O
"	O
editions	O
of	O
the	O
game	O
.	O
</s>
<s>
As	O
a	O
first-person	O
shooter	O
,	O
Call	B-Application
of	I-Application
Duty	I-Application
places	O
the	O
player	O
in	O
control	O
of	O
an	O
infantry	B-Protocol
soldier	O
who	O
makes	O
use	O
of	O
various	O
authentic	O
World	O
War	O
II	O
firearms	O
in	O
combat	O
.	O
</s>
<s>
Each	O
mission	O
features	O
a	O
series	O
of	O
objectives	O
that	O
are	O
marked	O
on	O
the	O
heads-up	B-Application
display	I-Application
's	O
compass	O
;	O
the	O
player	O
must	O
complete	O
all	O
objectives	O
to	O
advance	O
to	O
the	O
next	O
mission	O
.	O
</s>
<s>
The	O
player	O
can	O
save	O
and	O
load	O
at	O
any	O
time	O
,	O
rather	O
than	O
the	O
checkpoint	O
system	O
utilized	O
in	O
later	O
Call	B-Application
of	I-Application
Duty	I-Application
games	O
.	O
</s>
<s>
Unlike	O
later	O
Call	B-Application
of	I-Application
Duty	I-Application
games	O
,	O
the	O
first	O
allows	O
the	O
player	O
to	O
toggle	O
between	O
different	O
firing	O
modes	O
(	O
single	O
shot	O
or	O
automatic	O
fire	O
)	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
was	O
one	O
of	O
the	O
early	O
first-person	O
shooters	O
to	O
feature	O
iron	O
sights	O
in	O
game	O
play	O
;	O
by	O
pressing	O
the	O
corresponding	O
key	O
the	O
player	O
aims	O
down	O
the	O
gun	O
's	O
actual	O
sights	O
for	O
increased	O
accuracy	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
also	O
featured	O
"	O
shellshock	O
"	O
(	O
not	O
to	O
be	O
confused	O
with	O
the	O
psychological	O
condition	O
of	O
the	O
same	O
name	O
)	O
:	O
when	O
there	O
is	O
an	O
explosion	O
near	O
the	O
player	O
,	O
he	O
momentarily	O
experiences	O
simulated	O
tinnitus	O
,	O
appropriate	O
sound	O
"	O
muffling	O
"	O
effects	O
,	O
blurred	O
vision	O
,	O
and	O
also	O
results	O
in	O
the	O
player	O
slowing	O
down	O
,	O
unable	O
to	O
sprint	O
.	O
</s>
<s>
AI-controlled	O
soldiers	O
will	O
take	O
cover	O
behind	O
walls	O
,	O
barricades	O
,	O
and	O
other	O
obstacles	O
when	O
available	O
.	O
</s>
<s>
The	O
American	O
campaign	O
begins	O
in	O
August	O
1942	O
with	O
Private	O
Martin	O
,	O
a	O
newly	O
enlisted	O
member	O
of	O
the	O
506th	O
Parachute	O
Infantry	B-Protocol
Regiment	O
,	O
completing	O
basic	O
training	O
at	O
Camp	O
Toccoa	O
.	O
</s>
<s>
Martin	O
and	O
his	O
unit	O
are	O
sent	O
to	O
force	O
the	O
remaining	O
Germans	O
from	O
Sainte-Mère-Église	O
and	O
disable	O
several	O
Flakpanzers	O
(	O
anti-aircraft	O
tanks	O
)	O
as	O
D-Day	B-Application
begins	O
.	O
</s>
<s>
Martin	O
's	O
unit	O
later	O
takes	O
part	O
in	O
the	O
Battle	B-Device
of	I-Device
the	I-Device
Bulge	I-Device
,	O
successfully	O
securing	O
top-secret	O
documents	O
and	O
stopping	O
an	O
attempt	O
by	O
the	O
Germans	O
to	O
call	O
in	O
tanks	O
.	O
</s>
<s>
The	O
unit	O
is	O
dropped	O
in	O
Horsa	O
gliders	O
near	O
Pegasus	B-Application
Bridge	I-Application
,	O
Bénouville	O
.	O
</s>
<s>
Later	O
,	O
Evans	O
,	O
Waters	O
and	O
their	O
squad	O
arrive	O
near	O
Burgsteinfurt	O
,	O
Germany	O
,	O
to	O
assist	O
the	O
impending	O
Allied	B-Application
assault	I-Application
on	O
the	O
city	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
was	O
developed	O
by	O
Infinity	O
Ward	O
,	O
a	O
new	O
studio	O
formed	O
in	O
2002	O
originally	O
consisting	O
of	O
21	O
employees	O
,	O
many	O
of	O
whom	O
were	O
project	O
lead	O
developers	O
of	O
the	O
successful	O
Medal	B-Application
of	I-Application
Honor	I-Application
:	I-Application
Allied	I-Application
Assault	I-Application
released	O
the	O
same	O
year	O
.	O
</s>
<s>
Using	O
an	O
enhanced	O
version	O
of	O
the	O
id	B-Application
Tech	I-Application
3	I-Application
game	O
engine	O
developed	O
for	O
Quake	B-Application
III	I-Application
Arena	I-Application
and	O
an	O
in-house	O
skeletal	O
animation	O
system	O
called	O
"	O
Ares	O
"	O
,	O
Infinity	O
Ward	O
set	O
out	O
to	O
develop	O
a	O
new	O
World	O
War	O
II-era	O
video	O
game	O
that	O
,	O
unlike	O
many	O
of	O
its	O
predecessors	O
,	O
placed	O
more	O
emphasis	O
on	O
squad-based	O
play	O
with	O
intelligent	O
assistance	O
from	O
teammates	O
during	O
large-scale	O
battles	O
.	O
</s>
<s>
Another	O
area	O
the	O
development	O
team	O
focused	O
on	O
was	O
their	O
artificial	B-Application
intelligence	I-Application
(	O
AI	B-Application
)	O
pathfinding	O
component	O
dubbed	O
"	O
Conduit	O
"	O
.	O
</s>
<s>
The	O
AI	B-Application
in	O
the	O
game	O
was	O
designed	O
to	O
flank	O
the	O
opponent	O
,	O
bank	O
grenades	O
,	O
and	O
move	O
from	O
one	O
cover	O
point	O
to	O
another	O
.	O
</s>
<s>
Lead	O
animation	O
director	O
Michael	O
Boon	O
explained	O
that	O
actions	O
which	O
would	O
have	O
normally	O
been	O
scripted	O
in	O
past	O
games	O
were	O
moved	O
to	O
a	O
dynamic	O
AI	B-Application
environment	O
,	O
in	O
order	O
to	O
help	O
create	O
a	O
different	O
experience	O
each	O
time	O
levels	O
are	O
replayed	O
.	O
</s>
<s>
While	O
the	O
campaigns	O
were	O
the	O
primary	O
focus	O
,	O
development	O
of	O
the	O
multiplayer	O
modes	O
were	O
tailored	O
to	O
please	O
modders	B-Device
.	O
</s>
<s>
Zied	O
Rieke	O
,	O
a	O
lead	O
designer	O
,	O
clarified	O
that	O
gameplay	O
and	O
modes	O
were	O
written	O
in	O
script	O
making	O
it	O
"	O
extremely	O
easy	O
for	O
players	O
to	O
make	O
their	O
own	O
modifications	O
to	O
Call	B-Application
of	I-Application
Duty	I-Application
multiplayer	O
"	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
received	O
"	O
critical	O
acclaim	O
"	O
,	O
according	O
to	O
review	B-Application
aggregator	I-Application
Metacritic	O
.	O
</s>
<s>
Computer	O
Games	O
Magazine	O
named	O
Call	B-Application
of	I-Application
Duty	I-Application
the	O
sixth-best	O
computer	O
game	O
of	O
2003	O
,	O
and	O
the	O
editors	O
wrote	O
,	O
"	O
This	O
game	O
ups	O
the	O
ante	O
in	O
the	O
WWII	O
shooter	O
arena	O
,	O
and	O
makes	O
everything	O
that	O
has	O
come	O
before	O
it	O
seem	O
as	O
outdated	O
as	O
France	O
's	O
army.	O
"	O
</s>
<s>
The	O
editors	O
of	O
Computer	O
Gaming	O
World	O
presented	O
Call	B-Application
of	I-Application
Duty	I-Application
with	O
their	O
2003	O
"	O
Shooter	O
of	O
the	O
Year	O
"	O
award	O
.	O
</s>
<s>
They	O
remarked	O
,	O
"	O
Call	B-Application
of	I-Application
Duty	I-Application
won	O
this	O
category	O
without	O
a	O
shot	O
fired	O
—	O
there	O
simply	O
was	O
no	O
debate.	O
"	O
</s>
<s>
The	O
N-Gage	B-Device
version	O
got	O
"	O
mixed	O
or	O
average	O
reviews	O
"	O
on	O
the	O
site	O
Metacritic	O
.	O
</s>
<s>
The	O
NPD	O
Group	O
named	O
Call	B-Application
of	I-Application
Duty	I-Application
the	O
eighth-best-selling	O
computer	O
game	O
of	O
2003	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
alone	O
,	O
Call	B-Application
of	I-Application
Duty	I-Application
sold	O
790,000	O
copies	O
and	O
earned	O
$29.6	O
million	O
by	O
August	O
2006	O
.	O
</s>
<s>
In	O
the	O
United	O
Kingdom	O
,	O
Call	B-Application
of	I-Application
Duty	I-Application
sold	O
95,000	O
copies	O
by	O
the	O
end	O
of	O
2003	O
,	O
which	O
made	O
it	O
88th-biggest	O
seller	O
across	O
all	O
platforms	O
that	O
year	O
.	O
</s>
<s>
Discussing	O
this	O
performance	O
,	O
Kristan	O
Reed	O
of	O
GamesIndustry.biz	O
wrote	O
that	O
"	O
Activision	O
will	O
be	O
pleased	O
that	O
it	O
managed	O
to	O
interrupt	O
the	B-Application
Sims	I-Application
party	O
"	O
with	O
the	O
game	O
's	O
release	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
ultimately	O
received	O
a	O
"	O
Silver	O
"	O
sales	O
award	O
from	O
the	O
Entertainment	O
and	O
Leisure	O
Software	O
Publishers	O
Association	O
(	O
ELSPA	O
)	O
,	O
indicating	O
sales	O
of	O
at	O
least	O
100,000	O
copies	O
in	O
the	O
United	O
Kingdom	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
ultimately	O
sold	O
4.5	O
million	O
copies	O
worldwide	O
by	O
2013	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
spawned	O
numerous	O
spin-offs	O
and	O
sequels	O
,	O
part	O
of	O
the	O
Call	B-Application
of	I-Application
Duty	I-Application
series	O
.	O
</s>
<s>
Its	O
expansion	O
pack	O
-	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
United	I-Application
Offensive	I-Application
was	O
developed	O
by	O
Gray	O
Matter	O
Studios	O
and	O
released	O
September	O
14	O
,	O
2004	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
2	I-Application
was	O
also	O
developed	O
by	O
Infinity	O
Ward	O
and	O
was	O
released	O
in	O
October	O
2005	O
.	O
</s>
<s>
Some	O
Call	B-Application
of	I-Application
Duty	I-Application
spinoffs	O
were	O
developed	O
for	O
consoles	O
,	O
such	O
as	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
Finest	I-Application
Hour	I-Application
by	O
Spark	O
Unlimited	O
and	O
Call	B-Application
of	I-Application
Duty	I-Application
2	I-Application
:	I-Application
Big	I-Application
Red	I-Application
One	I-Application
by	O
Gray	O
Matter	O
Studios	O
(	O
merged	O
into	O
Treyarch	O
)	O
.	O
</s>
<s>
Call	B-Application
of	I-Application
Duty	I-Application
Classic	I-Application
is	O
a	O
downloadable	O
version	O
of	O
Call	B-Application
of	I-Application
Duty	I-Application
for	O
Xbox	B-Operating_System
360	I-Operating_System
and	O
PlayStation	B-Operating_System
3	I-Operating_System
,	O
featuring	O
HD	O
resolutions	O
.	O
</s>
<s>
Tokens	O
to	O
download	O
the	O
game	O
ahead	O
of	O
its	O
release	O
were	O
sold	O
along	O
with	O
special	O
"	O
Hardened	O
"	O
and	O
"	O
Prestige	O
"	O
editions	O
of	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
Modern	I-Application
Warfare	I-Application
2	I-Application
,	O
and	O
the	O
game	O
was	O
publicly	O
released	O
on	O
December	O
2	O
,	O
2009	O
.	O
</s>
