<s>
Metal	B-Application
Gear	I-Application
Solid	I-Application
:	I-Application
Portable	I-Application
Ops	I-Application
,	O
officially	O
abbreviated	O
MPO	O
,	O
is	O
a	O
2006	O
action-adventure	O
stealth	O
video	O
game	O
developed	O
by	O
Kojima	O
Productions	O
and	O
published	O
by	O
Konami	O
for	O
the	O
PlayStation	B-Operating_System
Portable	I-Operating_System
.	O
</s>
<s>
While	O
not	O
the	O
first	O
Metal	B-Application
Gear	I-Application
game	O
for	O
the	O
PSP	B-Operating_System
,	O
unlike	O
the	O
previously	O
released	O
Metal	B-Application
Gear	I-Application
Acid	I-Application
and	O
its	B-Application
sequel	I-Application
,	O
as	O
well	O
as	O
the	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
:	O
Digital	O
Graphic	O
Novel	O
,	O
it	O
retains	O
the	O
action-based	B-Application
play	I-Application
mechanics	I-Application
from	O
the	O
mainline	O
series	O
.	O
</s>
<s>
Set	O
in	O
1970	O
,	O
six	O
years	O
after	O
the	O
events	O
of	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
3	I-Application
:	I-Application
Snake	I-Application
Eater	I-Application
,	O
the	O
game	O
follows	O
the	O
exploits	O
of	O
Naked	O
Snake	O
after	O
he	O
finds	O
himself	O
captured	O
in	O
Colombia	O
by	O
the	O
now	O
renegade	O
FOX	O
unit	O
.	O
</s>
<s>
Portable	B-Application
Ops	I-Application
draws	O
heavily	O
from	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
3	I-Application
:	I-Application
Snake	I-Application
Eater	I-Application
,	O
utilizing	O
the	O
camera	O
system	O
from	O
the	O
Subsistence	O
edition	O
of	O
the	O
game	O
.	O
</s>
<s>
Alternatively	O
,	O
by	O
accessing	O
the	O
PSP	B-Operating_System
in	O
certain	O
hotspots	B-Application
using	O
the	O
system	O
's	O
Wi-Fi	O
feature	O
,	O
soldiers	O
and	O
even	O
special	O
bonus	O
characters	O
can	O
be	O
recruited	O
.	O
</s>
<s>
The	O
PSP	B-Operating_System
GPS	O
Receiver	O
can	O
also	O
be	O
used	O
to	O
similar	O
effect	O
.	O
</s>
<s>
The	O
player	O
can	O
also	O
recruit	O
the	O
GRU	O
,	O
KGB	B-Application
and	O
Ocelot	B-Application
unit	I-Application
soldiers	O
from	O
MGS3	B-Application
,	O
but	O
these	O
are	O
only	O
attainable	O
by	O
AP	O
Scan	O
.	O
</s>
<s>
The	O
game	O
contains	O
a	O
Wi-Fi-enabled	O
multiplayer	O
mode	O
,	O
which	O
is	O
an	O
expansion	O
of	O
the	O
"	O
Metal	B-Application
Gear	I-Application
Online	O
"	O
mode	O
previously	O
featured	O
in	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
3	I-Application
:	O
Subsistence	O
.	O
</s>
<s>
This	O
style	O
was	O
previously	O
utilized	O
in	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
:	O
Digital	O
Graphic	O
Novel	O
.	O
</s>
<s>
Portable	B-Application
Ops	I-Application
takes	O
place	O
in	O
1970	O
,	O
six	O
years	O
after	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
3	I-Application
:	I-Application
Snake	I-Application
Eater	I-Application
.	O
</s>
<s>
Other	O
characters	O
include	O
Ghost	O
(	O
Brian	O
Cummings/Naoki	O
Tatsuta	O
)	O
,	O
an	O
informant	O
who	O
comes	O
into	O
contact	O
with	O
Snake	O
,	O
revealing	O
the	O
existence	O
of	O
ICBMG	O
,	O
the	O
new	O
Metal	B-Application
Gear	I-Application
prototype	O
,	O
Ocelot	O
(	O
Josh	O
Keaton/Takumi	O
Yamazaki	O
)	O
,	O
a	O
former	O
Spetsnaz	O
Major	O
who	O
assists	O
Gene	O
from	O
behind-the-scenes	O
,	O
EVA	O
(	O
Vanessa	O
Marshall/Misa	O
Watanabe	O
)	O
,	O
a	O
spy	O
for	O
the	O
PLA	O
who	O
assisted	O
Snake	O
in	O
Snake	O
Eater	O
,	O
and	O
Raikov	O
(	O
Charlie	O
Schlatter/Kenyu	O
Horiuchi	O
)	O
,	O
a	O
GRU	O
Major	O
.	O
</s>
<s>
Teliko	B-Application
Friedman	I-Application
(	O
Kari	O
Wahlgren/Yūko	O
Nagashima	O
)	O
and	O
Venus	B-Application
(	O
Kathryn	O
Fiore/Rika	O
Komatsu	O
)	O
,	O
the	O
heroines	O
from	O
Metal	B-Application
Gear	I-Application
Acid	I-Application
and	O
Metal	B-Application
Gear	I-Application
Acid	I-Application
2	I-Application
respectively	O
,	O
can	O
both	O
be	O
added	O
to	O
the	O
player	O
's	O
squad	O
by	O
either	O
:	O
completing	O
certain	O
side-missions	O
or	O
by	O
starting	O
the	O
second	O
playthrough	O
with	O
save	O
data	O
from	O
their	O
respective	O
games	O
.	O
</s>
<s>
Snake	O
learns	O
through	O
Roy	O
that	O
they	O
are	O
on	O
the	O
San	B-Application
Hieronymo	I-Application
Peninsula	I-Application
(	O
a	O
Russian	O
transliteration	O
of	O
"	O
San	O
Jerónimo	O
Peninsula	O
"	O
)	O
or	O
"	O
La	O
Península	O
de	O
los	O
Muertos	O
"	O
,	O
the	O
site	O
of	O
an	O
abandoned	O
Soviet	O
missile	O
silo	O
in	O
Colombia	O
.	O
</s>
<s>
Your	O
son	O
will	O
save	O
the	O
world.	O
”	O
Snake	O
destroys	O
an	O
experimental	O
model	O
of	O
the	O
ICBMG	O
(	O
the	O
Metal	B-Application
Gear	I-Application
model	O
)	O
codenamed	O
RAXA	O
and	O
eventually	O
defeats	O
Gene	O
,	O
destroying	O
the	O
finished	O
ICBMG	O
model	O
afterward	O
.	O
</s>
<s>
The	O
game	O
was	O
conceptualized	O
when	O
the	O
Kojima	O
Productions	O
staff	O
decided	O
to	O
make	O
the	O
first	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
chapter	O
rather	O
than	O
another	O
spin-off	O
for	O
the	O
PlayStation	B-Operating_System
Portable	I-Operating_System
.	O
</s>
<s>
Most	O
of	O
the	O
staff	O
had	O
previously	O
worked	O
in	O
the	O
spin-off	O
Metal	B-Application
Gear	I-Application
Acid	I-Application
2	I-Application
making	O
Portable	B-Application
Ops	I-Application
their	O
first	O
time	O
doing	O
a	O
main	O
installment	O
.	O
</s>
<s>
Their	O
biggest	O
challenge	O
was	O
adapting	O
the	O
play	O
mechanics	O
from	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
3	I-Application
:	O
Subsistence	O
(	O
the	O
latest	O
console	O
installment	O
at	O
the	O
time	O
)	O
to	O
Portable	B-Application
Ops	I-Application
as	O
the	O
PlayStation	B-Operating_System
Portable	I-Operating_System
lacked	O
a	O
right	O
analog	O
.	O
</s>
<s>
Since	O
players	O
cannot	O
spin	O
the	O
camera	O
with	O
the	O
PlayStation	B-Operating_System
Portable	I-Operating_System
the	O
game	O
added	O
a	O
sound	O
indicator	O
system	O
that	O
helps	O
them	O
to	O
see	O
where	O
there	O
are	O
enemies	O
.	O
</s>
<s>
Impressed	O
with	O
Ashley	O
Wood	O
's	O
work	O
in	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
:	O
Digital	O
Graphic	O
Novel	O
the	O
studio	O
asked	O
his	O
collaboration	O
to	O
illustrate	O
the	O
events	O
accompanied	O
with	O
voice-overs	O
from	O
the	O
story	O
replacing	O
the	O
typical	O
use	O
of	O
real	O
time	O
graphics	O
previously	O
used	O
for	O
cutscenes	O
.	O
</s>
<s>
MPO	O
is	O
notably	O
the	O
first	O
Metal	B-Application
Gear	I-Application
game	O
for	O
a	O
portable	O
platform	O
that	O
was	O
written	O
to	O
be	O
part	O
of	O
the	O
series	O
 '	O
main	O
continuity	O
.	O
</s>
<s>
However	O
,	O
the	O
game	O
was	O
not	O
directed	O
nor	O
written	O
by	O
Hideo	O
Kojima	O
(	O
who	O
at	O
the	O
time	O
was	O
leading	O
the	O
development	O
of	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
4	I-Application
:	I-Application
Guns	I-Application
of	I-Application
the	I-Application
Patriots	I-Application
on	O
PlayStation	B-Operating_System
3	I-Operating_System
)	O
,	O
but	O
by	O
a	O
separate	O
team	O
led	O
by	O
Masahiro	O
Yamamoto	O
and	O
written	O
by	O
Japanese	O
novelist	O
Gakuto	O
Mikumo	O
.	O
</s>
<s>
The	O
marketing	O
for	O
MPO	O
attempted	O
to	O
distance	O
the	O
game	O
from	O
prior	O
Metal	B-Application
Gear	I-Application
entries	O
on	O
portable	O
platforms	O
,	O
particularly	O
the	O
2D	O
action	B-Application
game	I-Application
Metal	B-Application
Gear	I-Application
:	I-Application
Ghost	I-Application
Babel	I-Application
for	O
the	O
Game	B-Device
Boy	I-Device
Color	I-Device
and	O
the	O
turn-based	O
Metal	B-Application
Gear	I-Application
Acid	I-Application
series	O
also	O
on	O
PSP	B-Operating_System
(	O
both	O
which	O
were	O
set	O
in	O
their	O
own	O
alternate	O
continuity	O
)	O
,	O
with	O
one	O
promotional	O
video	O
on	O
the	O
official	O
English	O
website	O
(	O
narrated	O
by	O
Ryan	O
Payton	O
,	O
Kojima	O
Productions	O
 '	O
international	O
coordinator	O
at	O
the	O
time	O
)	O
referring	O
to	O
MPO	O
as	O
"	O
a	O
true	O
action-based	O
chapter	O
in	O
the	O
Metal	B-Application
Gear	I-Application
Saga.	O
"	O
</s>
<s>
This	O
would	O
carry	O
over	O
with	O
the	O
promotion	O
of	O
the	O
series	O
 '	O
20th	O
Anniversary	O
campaign	O
,	O
in	O
which	O
MPO	O
was	O
packaged	O
alongside	O
the	O
three	O
mainline	O
MGS	O
games	O
at	O
the	O
time	O
as	O
part	O
of	O
a	O
box	O
set	O
released	O
in	O
Japan	O
,	O
and	O
later	O
on	O
with	O
the	O
release	O
of	O
MGS4	B-Application
,	O
in	O
which	O
the	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
4	I-Application
:	O
Database	O
(	O
a	O
downloadable	O
encyclopedia	O
for	O
the	B-Operating_System
PS3	I-Operating_System
covering	O
the	O
lore	O
of	O
the	O
Metal	B-Application
Gear	I-Application
series	I-Application
up	O
to	O
that	O
point	O
)	O
include	O
entries	O
for	O
characters	O
,	O
items	O
and	O
events	O
depicted	O
in	O
MPO	O
.	O
</s>
<s>
Kojima	O
also	O
claimed	O
that	O
MPO	O
was	O
a	O
necessary	O
component	O
to	O
the	O
story	O
of	O
MGS4	B-Application
,	O
to	O
the	O
extent	O
that	O
he	O
refused	O
to	O
finalize	O
the	O
story	O
for	O
MGS4	B-Application
until	O
after	O
the	O
story	O
for	O
MPO	O
was	O
finalized	O
.	O
</s>
<s>
This	O
would	O
change	O
when	O
Kojima	O
started	O
the	O
development	O
of	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
:	I-Application
Peace	I-Application
Walker	I-Application
(	O
or	O
MGSPW	B-Application
)	O
,	O
a	O
later	O
action-based	O
entry	O
also	O
released	O
on	O
the	O
PSP	B-Operating_System
.	O
</s>
<s>
Unlike	O
MPO	O
,	O
MGSPW	B-Application
was	O
directed	O
and	O
written	O
by	O
Kojima	O
,	O
much	O
like	O
the	O
numbered	O
console	O
entries	O
of	O
the	O
series	O
.	O
</s>
<s>
Set	O
four	O
years	O
after	O
the	O
events	O
of	O
MPO	O
,	O
MGSPW	B-Application
would	O
be	O
written	O
as	O
a	O
direct	O
sequel	O
to	O
MGS3	B-Application
and	O
the	O
events	O
of	O
MPO	O
are	O
only	O
given	O
one	O
brief	O
direct	O
mention	O
by	O
one	O
character	O
.	O
</s>
<s>
Kojima	O
describes	O
MGSPW	B-Application
as	O
a	O
true	O
mainline	O
installment	O
in	O
the	O
series	O
,	O
contrasting	O
it	O
with	O
MPO	O
and	O
the	O
Acid	O
series	O
(	O
which	O
he	O
regards	O
as	O
spinoffs	O
)	O
.	O
</s>
<s>
The	O
official	O
timelines	O
and	O
retrospectives	O
published	O
by	O
Kojima	O
Productions	O
since	O
then	O
tend	O
to	O
omit	O
MPO	O
as	O
a	O
canonical	O
entry	O
,	O
with	O
the	O
25th	O
Anniversary	O
page	O
going	O
as	O
far	O
as	O
to	O
describe	O
MGSPW	B-Application
as	O
the	O
"	O
first	O
game	O
in	O
the	O
canonical	O
Metal	B-Application
Gear	I-Application
Saga	O
released	O
for	O
the	O
PlayStation	B-Operating_System
Portable	I-Operating_System
platform	O
"	O
,	O
<ref name=truthmgspw>{{cite web|url=Metal Gear Solid: Peace Walker on "The Truth Behind Metal Gear Solid|language=ja|quote=本作は『メタルギア』サーガ（本史）初の携帯ゲーム機プレイステーション・ポータブル用ソフトである。}}</ref>	O
while	O
the	O
summary	O
of	O
MGSPW	B-Application
on	O
the	O
main	O
page	O
describing	O
Metal	B-Application
Gear	I-Application
ZEKE	O
as	O
the	O
"	O
world	O
's	O
first	O
Metal	O
Gear.	O
"	O
</s>
<s>
Kojima	O
would	O
later	O
clarify	O
his	O
stance	O
on	O
MPO	O
,	O
saying	O
that	O
he	O
views	O
the	O
series	O
 '	O
canon	O
from	O
an	O
authoritative	O
status	O
,	O
setting	O
apart	O
the	O
Metal	B-Application
Gear	I-Application
games	O
that	O
he	O
personally	O
worked	O
on	O
(	O
which	O
carry	O
the	O
"	O
A	O
Hideo	O
Kojima	O
Game	O
"	O
byline	O
)	O
from	O
the	O
games	O
that	O
he	O
only	O
worked	O
on	O
as	O
a	O
producer	O
or	O
did	O
n't	O
have	O
a	O
direct	O
involvement	O
in	O
its	O
development	O
.	O
</s>
<s>
In	O
Japan	O
,	O
it	O
was	O
released	O
two	O
weeks	O
later	O
,	O
on	O
December	O
21	O
,	O
in	O
two	O
limited	O
edition	O
packages	O
,	O
with	O
both	O
of	O
them	O
sharing	O
most	O
of	O
its	O
unique	O
bonus	O
content	O
,	O
such	O
as	O
a	O
special	O
camouflage	O
for	O
the	O
PlayStation	B-Operating_System
Portable	I-Operating_System
,	O
as	O
well	O
as	O
a	O
set	O
of	O
three	O
original	O
lapel	O
pins	O
.	O
</s>
<s>
On	O
November	O
1	O
,	O
2009	O
,	O
the	O
game	O
was	O
released	O
digitally	O
on	O
the	O
PlayStation	O
Store	O
on	O
the	O
PSP	B-Operating_System
in	O
all	O
three	O
regions	O
.	O
</s>
<s>
In	O
June	O
2016	O
,	O
the	O
game	O
PSP	B-Operating_System
digital	O
version	O
of	O
the	O
game	O
was	O
also	O
made	O
available	O
for	O
the	O
PlayStation	B-Device
Vita	I-Device
and	O
PlayStation	B-Device
TV	I-Device
.	O
</s>
<s>
The	O
musical	O
score	O
of	O
Portable	B-Application
Ops	I-Application
was	O
composed	O
by	O
Norihiko	O
Hibino	O
,	O
Takahiro	O
Izutani	O
,	O
Yoshitaka	O
Suzuki	O
,	O
Kazuma	O
Jinnouchi	O
,	O
Nobuko	O
Toda	O
and	O
Akihiro	O
Honda	O
.	O
</s>
<s>
"	O
Calling	O
to	O
the	O
Night	O
"	O
was	O
later	O
featured	O
in	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
4	I-Application
:	I-Application
Guns	I-Application
of	I-Application
the	I-Application
Patriots	I-Application
as	O
an	O
iPod	B-Device
track	O
,	O
and	O
Nintendo	O
's	O
Super	B-Application
Smash	I-Application
Bros	I-Application
.	I-Application
Brawl	I-Application
as	O
one	O
of	O
the	O
songs	O
played	O
on	O
the	O
Shadow	O
Moses	O
Island	O
stage	O
.	O
</s>
<s>
The	O
song	O
was	O
used	O
in	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
:	I-Application
Peace	I-Application
Walker	I-Application
as	O
a	O
playable	O
in-game	O
track	O
via	O
the	O
Walkman	O
tool	O
.	O
</s>
<s>
ReceptionMetal	O
Gear	O
Solid	O
:	O
Portable	B-Application
Ops	I-Application
received	O
positive	O
reviews	O
.	O
</s>
<s>
Portable	B-Application
Ops	I-Application
PlusMetal	O
Gear	O
Solid	O
:	O
Portable	B-Application
Ops	I-Application
Plus	O
(	O
officially	O
abbreviated	O
MPO+	O
)	O
is	O
a	O
stand-alone	O
expansion	O
of	O
the	O
original	O
MPO	O
,	O
focused	O
primarily	O
on	O
online	O
play	O
.	O
</s>
<s>
Old	O
Snake	O
from	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
4	I-Application
and	O
Raiden	O
from	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
2	O
are	O
now	O
unlockable	O
for	O
completing	O
Infinity	O
Mission	O
mode	O
on	O
Normal	O
and	O
Hard	O
respectively	O
,	O
along	O
with	O
Roy	O
Campbell	O
when	O
completing	O
Extreme	O
.	O
</s>
<s>
Johnny	O
the	O
Guard	O
from	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
3	I-Application
can	O
also	O
be	O
found	O
as	O
a	O
random	O
prisoner	O
in	O
certain	O
stages	O
.	O
</s>
<s>
New	O
soldier	O
types	O
can	O
be	O
recruited	O
such	O
as	O
female	O
Soviet	O
soldiers	O
,	O
the	O
arctic	O
Genome	B-Application
Soldiers	I-Application
from	O
the	O
original	O
Metal	B-Application
Gear	I-Application
Solid	I-Application
and	O
the	O
various	O
enemy	O
soldier	O
types	O
from	O
MGS2	O
.	O
</s>
<s>
There	O
are	O
also	O
female	O
members	O
of	O
the	O
Ocelot	B-Application
Unit	I-Application
from	O
MGS3	B-Application
,	O
but	O
these	O
can	O
only	O
be	O
recruited	O
through	O
the	O
game	O
's	O
"	O
AP	O
Scout	O
"	O
feature	O
,	O
in	O
which	O
the	O
player	O
recruit	O
soldiers	O
through	O
LAN	O
access	O
points	O
.	O
</s>
