<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
is	O
a	O
2009	O
first-person	O
shooter	O
game	O
developed	O
and	O
published	O
by	O
Valve	O
.	O
</s>
<s>
The	O
sequel	O
to	O
Turtle	O
Rock	O
Studios	O
's	O
Left	B-Application
4	I-Application
Dead	I-Application
(	O
2008	O
)	O
and	O
the	O
second	O
game	O
in	O
the	O
Left	B-Application
4	I-Application
Dead	I-Application
series	O
,	O
it	O
was	O
released	O
for	O
Microsoft	B-Application
Windows	I-Application
and	O
Xbox	B-Operating_System
360	I-Operating_System
in	O
November	O
2009	O
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
in	O
October	O
2010	O
,	O
and	O
Linux	B-Application
in	O
July	O
2013	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
builds	O
upon	O
cooperatively	O
focused	O
gameplay	O
and	O
Valve	O
's	O
proprietary	O
Source	B-Application
engine	I-Application
,	O
the	O
same	O
game	O
engine	O
used	O
in	O
the	O
original	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
Set	O
during	O
the	O
aftermath	O
of	O
an	O
apocalyptic	O
pandemic	O
,	O
the	O
game	O
focuses	O
on	O
four	O
new	O
Survivors	O
,	O
fighting	O
against	O
hordes	O
of	O
zombies	B-Application
known	O
as	O
the	O
Infected	O
,	O
who	O
develop	O
severe	O
psychosis	O
and	O
act	O
extremely	O
aggressive	O
.	O
</s>
<s>
The	O
gameplay	O
is	O
procedurally	O
altered	O
by	O
the	O
"	O
AI	B-Application
Director	O
2.0	O
"	O
,	O
which	O
monitors	O
the	O
players	O
 '	O
performance	O
and	O
adjusts	O
the	O
scenario	O
to	O
provide	O
a	O
dynamic	O
challenge	O
.	O
</s>
<s>
Like	O
its	O
predecessor	B-Application
,	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
is	O
a	O
first-person	O
shooter	O
with	O
a	O
heavy	O
emphasis	O
on	O
cooperative	O
gameplay	O
.	O
</s>
<s>
As	O
in	O
the	B-Application
first	I-Application
game	I-Application
,	O
each	O
campaign	O
is	O
presented	O
in	O
menus	O
and	O
loading	O
screens	O
as	O
a	O
film	O
starring	O
the	O
four	O
Survivors	O
;	O
and	O
features	O
,	O
upon	O
completing	O
a	O
campaign	O
,	O
a	O
faux	O
credits	O
screen	O
which	O
acts	O
as	O
the	O
final	O
scoreboard	O
for	O
the	O
players	O
and	O
recaps	O
certain	O
performance	O
statistics	O
for	O
the	O
group	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
includes	O
5	O
regular	O
game	O
modes	O
:	O
</s>
<s>
Special	O
Infected	O
are	O
randomly	O
assigned	O
to	O
Infected	O
players	O
;	O
they	O
cannot	O
control	O
the	O
Witch	B-Application
or	O
any	O
Common	O
Infected	O
.	O
</s>
<s>
Occasionally	O
,	O
as	O
determined	O
by	O
the	O
AI	B-Application
Director	O
,	O
certain	O
players	O
will	O
become	O
the	O
Tank	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
also	O
features	O
a	O
Realism	O
mode	O
,	O
which	O
can	O
be	O
enabled	O
at	O
any	O
difficulty	O
for	O
either	O
Campaign	O
or	O
Versus	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
Witch	B-Application
enemy	O
can	O
kill	O
any	O
Survivor	O
she	O
would	O
have	O
normally	O
incapacitated	O
(	O
on	O
difficulties	O
other	O
than	O
Easy	O
)	O
.	O
</s>
<s>
While	O
also	O
referred	O
to	O
as	O
zombies	B-Application
,	O
the	O
Infected	O
are	O
humans	O
who	O
have	O
contracted	O
a	O
mutated	O
strain	O
of	O
an	O
infection	O
,	O
though	O
neither	O
the	O
source	B-Application
nor	O
nature	O
of	O
this	O
"	O
Green	O
Flu	O
"	O
are	O
made	O
clear	O
in	O
the	O
games	O
.	O
</s>
<s>
Damage	O
to	O
the	O
infected	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
is	O
portrayed	O
more	O
realistically	O
,	O
with	O
bullets	O
and	O
melee	O
weapons	O
ripping	O
off	O
bits	O
of	O
flesh	O
and	O
,	O
in	O
some	O
cases	O
,	O
limbs	O
.	O
</s>
<s>
A	O
new	O
addition	O
to	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
is	O
the	O
Uncommon	O
Infected	O
unique	O
to	O
each	O
campaign	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Dead	O
Center	O
campaign	O
introduces	O
infected	O
CEDA	O
agents	O
in	O
hazmat	O
suits	O
,	O
making	O
them	O
fireproof	O
;	O
Dark	O
Carnival	O
includes	O
clowns	O
,	O
whose	O
squeaking	O
shoes	O
attract	O
small	O
hordes	O
of	O
Common	O
Infected	O
;	O
and	O
The	O
Parish	O
includes	O
infected	O
private	O
security	O
contractors	O
in	O
riot	O
gear	O
,	O
making	O
them	O
bulletproof	B-Application
from	O
the	O
front	O
.	O
</s>
<s>
As	O
in	O
the	B-Application
first	I-Application
game	I-Application
,	O
there	O
are	O
special	O
Infected	O
whose	O
mutations	O
grant	O
them	O
special	O
abilities	O
that	O
make	O
them	O
highly	O
dangerous	O
,	O
which	O
act	O
as	O
bosses	O
.	O
</s>
<s>
The	O
five	O
Special	O
Infected	O
from	O
the	B-Application
first	I-Application
game	I-Application
return	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
,	O
some	O
with	O
modified	O
behavior	O
and	O
skin	O
models	O
:	O
</s>
<s>
The	O
Witch	B-Application
:	O
a	O
crying	O
Infected	O
woman	O
who	O
,	O
when	O
provoked	O
by	O
either	O
damage	O
,	O
loud	O
sounds	O
,	O
light	O
,	O
or	O
proximity	O
of	O
survivors	O
,	O
will	O
attack	O
the	O
provoker	O
and	O
any	O
other	O
Survivors	O
after	O
her	O
provoker	O
is	O
dead	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
introduces	O
a	O
variant	O
of	O
the	O
Witch	B-Application
that	O
wanders	O
aimlessly	O
in	O
the	O
open	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
also	O
introduces	O
three	O
new	O
Special	O
Infected	O
,	O
voiced	O
by	O
Dee	O
Bradley	O
Baker	O
:	O
</s>
<s>
As	O
in	O
the	B-Application
first	I-Application
game	I-Application
,	O
an	O
artificial	B-Application
intelligence	I-Application
system	O
called	O
the	O
AI	B-Application
Director	O
drives	O
gameplay	O
by	O
procedurally	O
spawning	O
enemies	O
,	O
weapons	O
and	O
items	O
based	O
on	O
players	O
 '	O
performance	O
during	O
any	O
given	O
campaign	O
.	O
</s>
<s>
In	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
,	O
the	O
Director	O
has	O
been	O
improved	O
to	O
encourage	O
more	O
participation	O
by	O
players	O
,	O
forcing	O
players	O
through	O
difficult	O
gauntlets	O
to	O
reach	O
safety	O
.	O
</s>
<s>
Like	O
its	O
predecessor	B-Application
,	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
is	O
set	O
in	O
the	O
aftermath	O
of	O
a	O
worldwide	O
pandemic	O
of	O
a	O
disease	O
nicknamed	O
the	O
"	O
Green	O
Flu	O
"	O
,	O
which	O
rapidly	O
transforms	O
humans	O
into	O
zombie-like	O
creatures	O
and	O
mutated	O
forms	O
that	O
demonstrate	O
extreme	O
aggression	O
towards	O
non-infected	O
beings	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
introduces	O
four	O
new	O
survivors	O
:	O
Coach	O
,	O
Ellis	O
,	O
Nick	O
,	O
and	O
Rochelle	O
,	O
who	O
are	O
immune	O
to	O
the	O
disease	O
and	O
have	O
individual	O
backstories	O
that	O
are	O
provided	O
through	O
character	O
dialogue	O
.	O
</s>
<s>
While	O
the	O
game	O
is	O
intended	O
as	O
a	O
continuation	O
of	O
the	O
original	O
,	O
occurring	O
one	O
week	O
after	O
the	B-Application
first	I-Application
game	I-Application
begins	O
,	O
Valve	O
decided	O
to	O
create	O
a	O
new	O
group	O
of	O
survivors	O
due	O
to	O
the	O
change	O
in	O
location	O
.	O
</s>
<s>
Like	O
the	B-Application
first	I-Application
game	I-Application
,	O
the	O
five	O
campaigns	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
take	O
place	O
across	O
a	O
story	O
arc	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
features	O
a	O
new	O
cast	O
of	O
four	O
human	O
survivors	O
:	O
Coach	O
(	O
voiced	O
by	O
Chad	O
Coleman	O
)	O
,	O
a	O
stocky	O
high	O
school	O
football	O
coach	O
with	O
a	O
bad	O
knee	O
(	O
although	O
this	O
does	O
not	O
affect	O
gameplay	O
)	O
;	O
Nick	O
(	O
voiced	O
by	O
Canadian	O
singer	O
Hugh	O
Dillon	O
)	O
,	O
a	O
pessimistic	O
gambler	O
and	O
con	O
artist	O
;	O
Rochelle	O
(	O
voiced	O
by	O
Rochelle	O
Aytes	O
)	O
,	O
a	O
low-level	O
production	O
assistant	O
for	O
a	O
local	O
television	O
station	O
that	O
was	O
reporting	O
on	O
the	O
pandemic	O
;	O
and	O
Ellis	O
(	O
voiced	O
by	O
Eric	O
Ladin	O
)	O
,	O
a	O
friendly	O
and	O
talkative	O
redneck	O
mechanic	O
who	O
often	O
talks	O
about	O
his	O
friend	O
Keith	O
and	O
their	O
many	O
misadventures	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
four	O
playable	O
characters	O
,	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
also	O
features	O
two	O
supporting	O
characters	O
in	O
the	O
form	O
of	O
Whitaker	O
(	O
voiced	O
by	O
Dayton	O
Callie	O
)	O
,	O
a	O
gun	O
store	O
owner	O
,	O
and	O
Virgil	O
(	O
voiced	O
by	O
Randall	O
Newsome	O
)	O
,	O
a	O
Cajun	O
boat	O
captain	O
who	O
appears	O
(	O
voice	O
only	O
)	O
in	O
the	O
game	O
's	O
final	O
three	O
campaigns	O
.	O
</s>
<s>
The	O
Sacrifice	O
takes	O
place	O
before	O
the	O
main	O
events	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
and	O
after	O
the	O
events	O
of	O
comic	O
book	O
of	O
the	O
same	O
name	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
the	B-Application
first	I-Application
game	I-Application
,	O
the	O
original	O
survivors	O
—	O
Bill	O
,	O
Francis	O
,	O
Louis	O
,	O
and	O
Zoey	O
—	O
arrive	O
at	O
the	O
portside	O
town	O
of	O
Rayford	O
in	O
Georgia	O
in	O
order	O
to	O
search	O
for	O
a	O
boat	O
that	O
can	O
take	O
them	O
to	O
the	O
Florida	O
Keys	O
.	O
</s>
<s>
This	O
is	O
the	O
end	O
of	O
Bill	O
's	O
story	O
in	O
the	O
Left	B-Application
4	I-Application
Dead	I-Application
video	O
game	O
series	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
opens	O
in	O
Dead	O
Center	O
(	O
set	O
in	O
Savannah	O
,	O
Georgia	O
)	O
,	O
where	O
the	O
four	O
survivors	O
find	O
themselves	O
abandoned	O
on	O
a	O
hotel	O
roof	O
by	O
rescue	O
helicopters	O
.	O
</s>
<s>
After	O
fighting	O
their	O
way	O
through	O
a	O
wedding	O
reception	O
(	O
complete	O
with	O
a	O
Witch	B-Application
bride	O
)	O
,	O
the	O
streets	O
,	O
and	O
a	O
historic	O
under-the-river	O
tour	O
,	O
they	O
meet	O
up	O
again	O
with	O
the	O
original	O
survivors	O
,	O
who	O
help	O
by	O
covering	O
for	O
the	O
group	O
while	O
they	O
fill	O
the	O
generator	O
and	O
lowering	O
the	O
bridge	O
once	O
it	O
's	O
full	O
.	O
</s>
<s>
When	O
the	O
pilot	O
starts	O
attacking	O
them	O
,	O
Nick	O
is	O
forced	O
to	O
kill	O
him	O
(	O
echoing	O
a	O
similar	O
situation	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
)	O
,	O
causing	O
the	O
chopper	O
to	O
crash	O
into	O
a	O
bayou	O
,	O
which	O
acts	O
as	O
the	O
setting	O
for	O
Swamp	O
Fever	O
.	O
</s>
<s>
As	O
a	O
tumultuous	O
hurricane	O
approaches	O
(	O
the	O
titular	O
Hard	O
Rain	O
of	O
the	O
subsequent	O
campaign	O
)	O
,	O
the	O
survivors	O
go	O
ashore	O
at	O
Ducatel	O
in	O
Mississippi	O
,	O
after	O
which	O
they	O
make	O
their	O
way	O
through	O
an	O
abandoned	O
(	O
and	O
Witch-infested	O
)	O
sugarcane	O
mill	O
to	O
a	O
gas	O
station	O
to	O
get	O
diesel	O
fuel	O
,	O
and	O
return	O
to	O
signal	O
Virgil	O
using	O
the	O
neon	O
sign	O
of	O
a	O
burger	O
chain	O
restaurant	O
.	O
</s>
<s>
Judging	O
from	O
their	O
dialogue	O
,	O
the	O
military	O
pilots	O
suspect	O
the	O
survivors	O
to	O
be	O
"	O
carriers	O
"	O
,	O
similar	O
to	O
the	O
original	O
survivors	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
Development	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
started	O
shortly	O
after	O
the	O
release	O
of	O
the	B-Application
first	I-Application
game	I-Application
—	O
following	O
a	O
short	O
break	O
—	O
building	O
on	O
ideas	O
from	O
the	O
development	O
team	O
to	O
make	O
the	O
next	O
game	O
"	O
bigger	O
and	O
better	O
"	O
.	O
</s>
<s>
The	O
game	O
was	O
given	O
the	O
code	O
name	O
"	O
Carnation	O
"	O
to	O
prevent	O
revealing	O
its	O
details	O
before	O
its	O
official	O
announcement	O
;	O
Valve	O
also	O
considered	O
a	O
new	O
title	O
for	O
the	O
game	O
,	O
Back	O
4	O
More	O
,	O
though	O
they	O
eventually	O
dropped	O
it	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
.	O
</s>
<s>
Chet	O
Faliszek	O
stated	O
that	O
Left	B-Application
4	I-Application
Dead	I-Application
2s	I-Application
story	O
would	O
explore	O
more	O
of	O
the	O
world	O
of	O
the	O
game	O
,	O
and	O
that	O
Valve	O
had	O
created	O
a	O
full	O
story	O
for	O
the	O
cause	O
and	O
effects	O
of	O
the	O
infection	O
pandemic	O
,	O
including	O
terms	O
that	O
they	O
have	O
used	O
for	O
the	O
AI	B-Application
Director	O
.	O
</s>
<s>
The	O
team	O
used	O
a	O
Left	B-Application
4	I-Application
Dead	I-Application
dictionary	O
developed	O
to	O
describe	O
level	O
design	O
and	O
flow	O
within	O
the	O
game	O
to	O
provide	O
a	O
common	O
language	O
for	O
developing	O
the	O
levels	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
contains	O
about	O
7,800	O
unique	O
lines	O
of	O
dialogue	O
,	O
a	O
40%	O
increase	O
over	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
In	O
development	O
,	O
the	O
programmers	O
wanted	O
to	O
find	O
a	O
way	O
to	O
provide	O
more	O
variation	O
and	O
visual	O
effects	O
for	O
the	O
players	O
,	O
although	O
they	O
were	O
already	O
strained	O
by	O
memory	O
limitations	O
on	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
for	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
They	O
had	O
simulated	O
this	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
by	O
having	O
five	O
possible	O
character	O
models	O
that	O
would	O
result	O
from	O
a	O
fatal	O
attack	O
but	O
felt	O
this	O
could	O
be	O
advanced	O
further	O
.	O
</s>
<s>
Already	O
limited	O
by	O
memory	O
concerns	O
on	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
that	O
prevented	O
further	O
variations	O
on	O
the	O
core	O
infected	O
models	O
,	O
the	O
team	O
devised	O
a	O
system	O
of	O
using	O
textures	O
with	O
transparencies	O
combined	O
with	O
ellipsoid	O
culling	O
from	O
any	O
infected	O
character	O
model	O
to	O
simulate	O
the	O
wounds	O
,	O
with	O
several	O
graphical	O
process	O
simplifications	O
to	O
avoid	O
taxing	O
the	O
rendering	O
system	O
.	O
</s>
<s>
This	O
allowed	O
the	O
team	O
to	O
simulate	O
up	O
to	O
two	O
such	O
wounds	O
on	O
each	O
infected	O
using	O
only	O
13%	O
of	O
the	O
memory	O
resources	O
of	O
the	O
based	O
system	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
The	O
water	O
maps	O
were	O
created	O
by	O
using	O
the	O
3D	O
animation	O
tool	O
Houdini	B-Application
against	O
its	O
landscape	O
maps	O
to	O
create	O
realistic	O
water	O
flow	O
patterns	O
as	O
surface	O
maps	O
.	O
</s>
<s>
These	O
water	O
effects	O
were	O
further	O
expanded	O
upon	O
for	O
Valve	O
's	O
next	O
game	O
,	O
Portal	B-Application
2	I-Application
.	O
</s>
<s>
Doug	O
Lombardi	O
,	O
vice-president	O
of	O
marketing	O
for	O
Valve	O
,	O
noted	O
that	O
the	O
SDK	B-Application
released	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
would	O
also	O
be	O
compatible	O
with	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
.	O
</s>
<s>
PC	O
and	O
Xbox	B-Operating_System
360	I-Operating_System
players	O
who	O
pre-ordered	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
through	O
participating	O
retailers	O
gained	O
early	O
access	O
to	O
the	O
game	O
's	O
demo	O
,	O
which	O
was	O
released	O
on	O
October	O
27	O
,	O
2009	O
for	O
Xbox	B-Operating_System
Live	O
and	O
October	O
28	O
,	O
2009	O
for	O
PC	O
players	O
,	O
and	O
an	O
exclusive	O
baseball	O
bat	O
melee	O
weapon	O
to	O
be	O
used	O
in	O
game	O
.	O
</s>
<s>
Pre-ordering	O
the	O
PC	O
version	O
of	O
the	O
game	O
through	O
the	O
Steam	B-Application
network	O
also	O
unlocks	O
Bill	O
's	O
beret	O
from	O
Left	B-Application
4	I-Application
Dead	I-Application
for	O
use	O
in	O
the	O
PC	O
version	O
of	O
Team	B-Application
Fortress	I-Application
2	I-Application
.	O
</s>
<s>
Also	O
,	O
when	O
a	O
person	O
buys	O
the	O
game	O
and	O
starts	O
up	O
Team	B-Application
Fortress	I-Application
2	I-Application
,	O
they	O
will	O
get	O
a	O
frying	O
pan	O
as	O
a	O
melee	O
weapon	O
and	O
Ellis	O
 '	O
hat	O
as	O
an	O
in-game	O
hat	O
.	O
</s>
<s>
The	O
demo	O
became	O
available	O
for	O
all	O
PC	O
and	O
Xbox	B-Operating_System
Live	O
Gold	O
users	O
on	O
November	O
4	O
,	O
2009	O
with	O
Xbox	B-Operating_System
Live	O
Silver	O
users	O
gaining	O
access	O
on	O
November	O
11	O
,	O
2009	O
.	O
</s>
<s>
On	O
October	O
5	O
,	O
2009	O
,	O
Valve	O
announced	O
that	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
would	O
be	O
promoted	O
by	O
a	O
$25million	O
advertising	O
campaign	O
,	O
exceeding	O
the	O
$10million	O
that	O
supported	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
was	O
released	O
on	O
Steam	B-Application
on	O
November	O
16	O
,	O
2009	O
.	O
</s>
<s>
In	O
March	O
2010	O
,	O
Valve	O
announced	O
that	O
it	O
would	O
be	O
bringing	O
the	O
Steam	B-Application
content	O
platform	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
computers	O
;	O
along	O
with	O
it	O
,	O
Steam	B-Application
will	O
be	O
providing	O
native	O
versions	O
of	O
existing	O
Valve	O
games	O
including	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
and	O
its	O
predecessor	B-Application
.	O
</s>
<s>
The	O
games	O
will	O
support	O
cross-platform	O
play	O
,	O
allowing	O
Mac	O
players	O
to	O
play	O
alongside	O
PC	O
players	O
on	O
the	O
same	O
servers	O
,	O
and	O
will	O
also	O
be	O
part	O
of	O
its	O
Steam	B-Application
Play	O
cross-compatible	O
and	O
Steam	B-Application
Cloud	O
titles	O
,	O
allowing	O
a	O
player	O
who	O
has	O
purchased	O
the	O
game	O
on	O
one	O
platform	O
to	O
download	O
and	O
play	O
it	O
on	O
the	O
other	O
platform	O
for	O
free	O
.	O
</s>
<s>
The	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
client	O
was	O
released	O
on	O
October	O
5	O
,	O
2010	O
.	O
</s>
<s>
With	O
the	O
introduction	O
of	O
a	O
Linux	B-Application
client	O
for	O
Steam	B-Application
,	O
Valve	O
has	O
affirmed	O
that	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
will	O
be	O
developed	O
for	O
Linux	B-Application
.	O
</s>
<s>
The	O
Linux	B-Application
version	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
was	O
released	O
on	O
May	O
3	O
,	O
2013	O
.	O
</s>
<s>
On	O
December	O
14	O
,	O
2009	O
,	O
Valve	O
announced	O
the	O
first	O
DLC	B-Protocol
installment	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
,	O
"	O
The	O
Passing	O
"	O
.	O
</s>
<s>
The	O
content	O
costs	O
560	O
Microsoft	B-Device
Points	I-Device
(	O
$6.99	O
)	O
for	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
and	O
is	O
free	O
for	O
PC	O
and	O
Mac	O
users	O
.	O
</s>
<s>
The	O
campaign	O
,	O
taking	O
place	O
between	O
the	O
"	O
Dead	O
Center	O
"	O
and	O
"	O
Dark	O
Carnival	O
"	O
campaigns	O
,	O
features	O
the	O
cast	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
meeting	O
with	O
three	O
of	O
the	O
survivors	O
from	O
the	O
original	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
"	O
The	O
Passing	O
"	O
contains	O
references	O
to	O
other	O
zombie-themed	O
works	O
,	O
including	O
the	O
games	O
Dead	B-Application
Rising	I-Application
(	O
2006	O
)	O
and	O
Plants	B-Application
vs.	I-Application
Zombies	I-Application
(	O
2009	O
)	O
,	O
and	O
the	O
film	O
28	O
Days	O
Later	O
(	O
2002	O
)	O
.	O
</s>
<s>
A	O
prequel	O
to	O
"	O
The	O
Passing	O
"	O
,	O
titled	O
"	O
The	O
Sacrifice	O
"	O
,	O
was	O
released	O
on	O
October	O
5	O
,	O
2010	O
,	O
as	O
an	O
add-on	O
for	O
both	O
Left	B-Application
4	I-Application
Dead	I-Application
and	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
.	O
</s>
<s>
This	O
prequel	O
ties	O
up	O
the	O
story	O
of	O
the	O
original	O
game	O
,	O
showing	O
the	O
events	O
leading	O
to	O
the	O
meeting	O
of	O
the	O
two	O
groups	O
of	O
survivors	O
in	O
"	O
The	O
Passing	O
"	O
from	O
the	O
point	O
of	O
the	O
Left	B-Application
4	I-Application
Dead	I-Application
characters	O
.	O
</s>
<s>
Valve	O
also	O
provided	O
the	O
full	O
"	O
No	O
Mercy	O
"	O
campaign	O
from	O
Left	B-Application
4	I-Application
Dead	I-Application
as	O
a	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
campaign	O
,	O
which	O
is	O
playable	O
with	O
the	O
original	O
Survivors	O
from	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
Though	O
the	O
maps	O
are	O
nearly	O
identical	O
to	O
their	O
appearance	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
,	O
No	O
Mercy	O
in	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
contains	O
all	O
of	O
the	O
enhancements	O
of	O
the	O
sequel	O
,	O
including	O
the	O
new	O
Special	O
Infected	O
,	O
Uncommon	O
Infected	O
,	O
melee	O
weapons	O
,	O
additional	O
guns	O
,	O
and	O
the	O
ability	O
to	O
use	O
the	O
new	O
game	O
modes	O
,	O
including	O
Mutations	O
and	O
Scavenge	O
mode	O
.	O
</s>
<s>
An	O
additional	O
community-created	O
downloadable	B-Protocol
content	I-Protocol
package	O
,	O
called	O
"	O
Cold	O
Stream	O
"	O
,	O
was	O
released	O
July	O
24	O
,	O
2012	O
for	O
Xbox	B-Operating_System
360	I-Operating_System
and	O
PC	O
.	O
</s>
<s>
Valve	O
has	O
announced	O
testing	O
had	O
begun	O
on	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
,	O
as	O
well	O
as	O
for	O
all	O
the	O
original	O
Left	B-Application
4	I-Application
Dead	I-Application
maps	O
via	O
L4D	B-Application
Blog	O
.	O
</s>
<s>
On	O
July	O
24	O
it	O
was	O
announced	O
that	O
Valve	O
did	O
not	O
send	O
the	O
downloadable	B-Protocol
content	I-Protocol
package	O
to	O
Microsoft	O
.	O
</s>
<s>
On	O
August	O
1	O
,	O
2012	O
,	O
it	O
was	O
announced	O
that	O
Cold	O
Stream	O
would	O
be	O
made	O
available	O
for	O
Xbox	B-Operating_System
360	I-Operating_System
on	O
August	O
3	O
,	O
at	O
the	O
price	O
point	O
of	O
560	O
MSP	O
(	O
$6.99	O
)	O
.	O
</s>
<s>
The	O
leads	O
on	O
the	O
community	O
project	O
had	O
worked	O
on	O
levels	O
and	O
had	O
pitched	O
the	O
idea	O
to	O
Valve	O
around	O
2019	O
,	O
but	O
at	O
that	O
time	O
,	O
the	O
studio	O
was	O
in	O
the	O
final	O
stages	O
of	O
finishing	O
Half-Life	B-Application
:	I-Application
Alyx	I-Application
,	O
but	O
gave	O
the	O
team	O
permission	O
to	O
continue	O
what	O
it	O
was	O
doing	O
,	O
including	O
providing	O
a	O
map	O
of	O
a	O
lighthouse	O
setting	O
(	O
the	O
origin	O
of	O
"	O
The	O
Last	O
Stand	O
"	O
name	O
)	O
that	O
was	O
used	O
in	O
the	O
original	O
Left	B-Application
4	I-Application
Dead	I-Application
as	O
a	O
Survival-mode	O
exclusive	O
map	O
.	O
</s>
<s>
Valve	O
subsequently	O
provided	O
minimal	O
technical	O
support	O
in	O
terms	O
of	O
Source	B-Application
engine	I-Application
support	O
,	O
leaving	O
the	O
community	O
team	O
to	O
handle	O
the	O
rest	O
.	O
</s>
<s>
The	O
film	O
's	O
director	O
,	O
Drew	O
Goddard	O
,	O
commented	O
on	O
what	O
the	O
downloadable	B-Protocol
content	I-Protocol
would	O
have	O
included	O
,	O
stating	O
:	O
"	O
The	O
game	O
was	O
gonna	O
be	O
amazing	O
.	O
</s>
<s>
Valve	O
did	O
allow	O
the	O
filmmakers	O
to	O
include	O
the	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
bosses	O
as	O
monsters	O
to	O
populate	O
some	O
of	O
the	O
scenes	O
in	O
the	O
film	O
despite	O
the	O
failed	O
project	O
.	O
</s>
<s>
On	O
April	O
4	O
,	O
2013	O
a	O
Resident	B-Application
Evil	I-Application
6	I-Application
crossover	O
DLC	B-Protocol
was	O
released	O
for	O
the	O
PC	O
version	O
.	O
</s>
<s>
It	O
adds	O
the	O
main	O
characters	O
and	O
two	O
monsters	O
from	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
to	O
the	O
PC-exclusive	O
The	O
Mercenaries	O
:	O
No	O
Mercy	O
mode	O
in	O
Resident	B-Application
Evil	I-Application
6	I-Application
.	O
</s>
<s>
Also	O
three	O
monsters	O
from	O
Resident	B-Application
Evil	I-Application
6	I-Application
are	O
added	O
as	O
replacement	O
skins	O
to	O
existing	O
monsters	O
on	O
the	O
PC	O
version	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
.	O
</s>
<s>
On	O
August	O
20	O
,	O
2015	O
,	O
an	O
update	O
for	O
the	O
game	O
Zombie	B-Application
Army	I-Application
Trilogy	I-Application
was	O
released	O
,	O
which	O
imported	O
the	O
eight	O
survivors	O
from	O
both	O
Left	B-Application
4	I-Application
Dead	I-Application
games	O
into	O
ZAT	O
.	O
</s>
<s>
In	O
2021	O
,	O
the	O
characters	O
were	O
added	O
to	O
the	O
games	O
sequel	O
Zombie	B-Application
Army	I-Application
4	I-Application
:	I-Application
Dead	I-Application
War	I-Application
.	O
</s>
<s>
Mutations	O
are	O
modifications	O
on	O
Left	B-Application
4	I-Application
Dead	I-Application
2s	I-Application
game	O
modes	O
,	O
which	O
have	O
been	O
offered	O
every	O
week	O
after	O
"	O
The	O
Passing	O
"	O
 '	O
s	O
release	O
;	O
these	O
game	O
modes	O
alter	O
the	O
conditions	O
of	O
play	O
.	O
</s>
<s>
All	O
Mutations	O
became	O
available	O
for	O
Xbox	B-Operating_System
360	I-Operating_System
users	O
with	O
the	O
release	O
of	O
Cold	O
Stream	O
.	O
</s>
<s>
Similar	O
to	O
Left	B-Application
4	I-Application
Dead	I-Application
and	O
other	O
Source	O
Engine-based	O
games	O
,	O
a	O
number	O
of	O
players	O
have	O
constructed	O
new	O
maps	O
,	O
campaigns	O
,	O
and	O
other	O
variations	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
,	O
supported	O
by	O
Valve	O
through	O
their	O
software	B-Application
development	I-Application
kit	I-Application
for	O
the	O
game	O
.	O
</s>
<s>
With	O
the	O
kit	O
,	O
players	O
have	O
found	O
ways	O
to	O
include	O
the	O
original	O
Left	B-Application
4	I-Application
Dead	I-Application
campaigns	O
into	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
.	O
</s>
<s>
Valve	O
updated	O
the	O
game	O
in	O
January	O
2013	O
to	O
include	O
support	O
for	O
Steam	B-Application
Workshop	O
,	O
allowing	O
users	O
to	O
create	O
and	O
share	O
new	O
scenarios	O
,	O
maps	O
,	O
characters	O
and	O
weapons	O
,	O
and	O
to	O
create	O
Mutation-like	O
changes	O
that	O
can	O
be	O
applied	O
to	O
existing	O
maps	O
.	O
</s>
<s>
A	O
further	O
patch	O
in	O
February	O
2013	O
introduced	O
a	O
new	O
scripting	O
system	O
,	O
Expanded	O
Mutation	O
System	O
,	O
that	O
gives	O
programmers	O
more	O
control	O
and	O
options	O
to	O
create	O
new	O
Mutations	O
that	O
can	O
be	O
played	O
across	O
any	O
map	O
or	O
to	O
customize	O
behavior	O
in	O
specific	O
campaigns	O
;	O
one	O
such	O
user-created	O
Mutation	O
creates	O
an	O
experience	O
similar	O
to	O
the	O
Zombie	B-Application
mode	O
in	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
Black	I-Application
Ops	I-Application
II	I-Application
,	O
allowing	O
players	O
to	O
buy	O
weapons	O
and	O
barricades	O
to	O
fight	O
off	O
waves	O
of	O
zombies	B-Application
.	O
</s>
<s>
A	O
Japanese	O
arcade	O
cabinet	O
version	O
of	O
L4D2	B-Application
titled	O
was	O
developed	O
and	O
released	O
under	O
license	O
by	O
Taito	O
in	O
December	O
2014	O
.	O
</s>
<s>
The	O
plot	O
and	O
gameplay	O
remains	O
largely	O
unchanged	O
from	O
L4D2	B-Application
,	O
streamlined	O
and	O
modified	O
for	O
a	O
time-limited	O
arcade	O
environment	O
.	O
</s>
<s>
Confogl	O
is	O
a	O
set	O
of	O
rules	O
for	O
competitive	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
versus	O
which	O
standardizes	O
certain	O
elements	O
and	O
changes	O
the	O
distribution	O
of	O
items	O
and	O
weapons	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
received	O
"	O
generally	O
favorable	O
reviews	O
"	O
across	O
both	O
platforms	O
according	O
to	O
review	B-Application
aggregator	I-Application
website	O
Metacritic	O
.	O
</s>
<s>
Game	O
journalists	O
praised	O
the	O
changes	O
made	O
with	O
the	O
new	O
melee	O
weapons	O
and	O
firearms	O
,	O
the	O
new	O
strategies	O
introduced	O
through	O
the	O
new	O
special	O
infected	O
,	O
and	O
the	O
details	O
of	O
the	O
southern	O
locale	O
and	O
individual	O
campaigns	O
compared	O
with	O
the	O
campaigns	O
of	O
the	B-Application
first	I-Application
game	I-Application
.	O
</s>
<s>
IGN	O
considered	O
that	O
the	O
game	O
improved	O
on	O
the	O
first	O
in	O
every	O
way	O
,	O
and	O
that	O
anyone	O
who	O
liked	O
the	O
concepts	O
introduced	O
by	O
the	B-Application
first	I-Application
game	I-Application
should	O
buy	O
the	O
second	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
received	O
the	O
Best	O
Xbox	B-Operating_System
360	I-Operating_System
Game	O
award	O
at	O
the	O
2009	O
Spike	O
Video	O
Game	O
Awards	O
.	O
</s>
<s>
In	O
2016	O
,	O
it	O
won	O
the	O
"	O
Better	O
With	O
Friends	O
"	O
Award	O
in	O
the	O
first-ever	O
Steam	B-Application
Awards	O
.	O
</s>
<s>
The	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
version	O
of	O
the	O
game	O
was	O
noted	O
at	O
launch	O
for	O
having	O
serious	O
issues	O
with	O
lag	B-Application
and	O
slowdown	O
in	O
online	O
game	O
modes	O
,	O
the	O
majority	O
coming	O
from	O
using	O
the	O
game	O
's	O
dedicated	O
servers	O
.	O
</s>
<s>
According	O
to	O
Valve	O
,	O
these	O
problems	O
were	O
due	O
to	O
an	O
unexpectedly	O
huge	O
number	O
of	O
players	O
online	O
on	O
Xbox	B-Operating_System
LIVE	O
.	O
</s>
<s>
Pre-release	O
sales	O
estimates	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
were	O
positive	O
.	O
</s>
<s>
As	O
of	O
July	O
2009	O
,	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
ranked	O
first	O
in	O
purchase	O
intent	O
out	O
of	O
all	O
upcoming	O
games	O
,	O
with	O
9	O
out	O
of	O
10	O
polled	O
stating	O
that	O
they	O
would	O
buy	O
the	O
game	O
.	O
</s>
<s>
According	O
to	O
Lombardi	O
,	O
pre-orders	O
for	O
the	O
sequel	O
within	O
the	O
month	O
following	O
the	O
announcement	O
were	O
double	O
those	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
at	O
the	O
same	O
time	O
relative	O
to	O
release	O
date	O
.	O
</s>
<s>
In	O
a	O
press	O
release	O
on	O
October	O
5	O
,	O
2009	O
Valve	O
announced	O
that	O
,	O
based	O
on	O
the	O
strength	O
of	O
pre-orders	O
,	O
they	O
expect	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
to	O
be	O
the	O
fastest	O
selling	O
product	O
in	O
the	O
company	O
's	O
history	O
,	O
with	O
the	O
game	O
's	O
pre-release	O
sales	O
averaging	O
300%	O
greater	O
than	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
In	O
an	O
interview	O
in	O
November	O
2009	O
,	O
Chet	O
Faliszek	O
claimed	O
the	O
number	O
of	O
pre-sales	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
were	O
four	O
times	O
that	O
of	O
the	O
original	O
game	O
.	O
</s>
<s>
On	O
December	O
1	O
,	O
2009	O
,	O
Valve	O
reported	O
that	O
more	O
than	O
two	O
million	O
retailed	O
copies	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
were	O
sold	O
in	O
two	O
weeks	O
,	O
which	O
represents	O
"	O
more	O
than	O
double	O
"	O
the	O
sales	O
of	O
the	O
original	O
game	O
's	O
two	O
week	O
debut	O
.	O
</s>
<s>
According	O
to	O
the	O
NPD	O
Group	O
,	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
version	O
was	O
the	O
fifth	O
best-selling	O
retail	O
title	O
for	O
consoles	O
in	O
November	O
2009	O
,	O
with	O
over	O
744,000	O
copies	O
sold	O
.	O
</s>
<s>
In	O
February	O
2010	O
,	O
Electronic	O
Arts	O
,	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
retail	O
distributor	O
,	O
revealed	O
that	O
the	O
game	O
had	O
sold	O
2.9	O
million	O
on	O
retail	O
so	O
far	O
while	O
Forbes	O
wrote	O
that	O
more	O
than	O
4	O
million	O
copies	O
were	O
sold	O
at	O
stores	O
in	O
2009	O
.	O
</s>
<s>
Over	O
two	O
weeks	O
in	O
July	O
2010	O
,	O
approximately	O
12,000	O
owners	O
of	O
Call	B-Application
of	I-Application
Duty	I-Application
:	I-Application
Modern	I-Application
Warfare	I-Application
2	I-Application
were	O
mistakenly	O
banned	O
by	O
Valve's-Anti-Cheat	B-Application
system	I-Application
.	O
</s>
<s>
On	O
May	O
10	O
,	O
2011	O
,	O
Doug	O
Lombardi	O
mentioned	O
that	O
each	O
of	O
the	O
Left	B-Application
4	I-Application
Dead	I-Application
games	O
had	O
sold	O
three	O
million	O
copies	O
on	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
.	O
</s>
<s>
The	O
game	O
was	O
offered	O
free	O
for	O
a	O
day	O
on	O
Steam	B-Application
during	O
Christmas	O
2013	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
has	O
been	O
a	O
central	O
issue	O
in	O
a	O
number	O
of	O
critical	O
discussions	O
regarding	O
its	O
timing	O
and	O
its	O
graphic	O
and	O
mature	O
content	O
.	O
</s>
<s>
The	O
weekend	O
following	O
the	O
game	O
's	O
announcement	O
at	O
the	O
2009	O
E3	O
Convention	O
,	O
some	O
Left	B-Application
4	I-Application
Dead	I-Application
players	O
called	O
for	O
a	O
boycott	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
and	O
formed	O
the	O
Steam	B-Application
community	O
group	O
called	O
"	O
L4D2	B-Application
Boycott	O
(	O
NO-L4D2	O
)	O
"	O
which	O
grew	O
to	O
over	O
10,000	O
members	O
by	O
the	O
end	O
of	O
that	O
weekend	O
,	O
and	O
reached	O
more	O
than	O
37,000	O
about	O
a	O
month	O
later	O
.	O
</s>
<s>
In	O
addition	O
to	O
a	O
lack	O
of	O
further	O
Left	B-Application
4	I-Application
Dead	I-Application
content	O
,	O
they	O
were	O
concerned	O
with	O
the	O
characters	O
,	O
visuals	O
,	O
and	O
music	O
shown	O
in	O
the	O
E3	O
demonstration	O
video	O
,	O
feeling	O
these	O
were	O
inappropriate	O
to	O
the	B-Application
first	I-Application
game	I-Application
's	O
aesthetics	O
,	O
and	O
that	O
the	O
release	O
of	O
the	O
sequel	O
so	O
soon	O
after	O
the	B-Application
first	I-Application
game	I-Application
would	O
fracture	O
the	O
community	O
.	O
</s>
<s>
In	O
response	O
to	O
these	O
complaints	O
,	O
Valve	O
marketer	O
Doug	O
Lombardi	O
stated	O
that	O
the	O
announcement	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
at	O
E3	O
should	O
not	O
be	O
taken	O
to	O
indicate	O
that	O
Valve	O
would	O
no	O
longer	O
support	O
the	B-Application
first	I-Application
game	I-Application
.	O
</s>
<s>
He	O
asked	O
the	O
community	O
to	O
"	O
trust	O
 [ them ] 	O
a	O
little	O
bit	O
,	O
"	O
and	O
told	O
them	O
that	O
while	O
their	O
team	O
was	O
eager	O
to	O
get	O
new	O
material	O
to	O
players	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
,	O
they	O
determined	O
that	O
a	O
sequel	O
would	O
be	O
the	O
best	O
option	O
for	O
several	O
reasons	O
:	O
the	O
demand	O
for	O
new	O
campaigns	O
,	O
enemies	O
and	O
weapons	O
could	O
not	O
be	O
met	O
as	O
a	O
simple	O
DLC	B-Protocol
;	O
both	O
Faliszek	O
and	O
project	O
lead	O
Tom	O
Leonard	O
found	O
that	O
too	O
much	O
of	O
the	O
content	O
relied	O
on	O
each	O
other	O
,	O
making	O
it	O
very	O
difficult	O
to	O
release	O
incremental	O
patches	O
in	O
the	O
same	O
style	O
as	O
Team	B-Application
Fortress	I-Application
2	I-Application
;	O
the	O
development	O
team	O
liked	O
the	O
idea	O
of	O
rolling	O
up	O
the	O
content	O
into	O
a	O
sequel	O
to	O
be	O
released	O
a	O
year	O
after	O
Left	B-Application
4	I-Application
Deads	I-Application
release	O
.	O
</s>
<s>
In	O
September	O
2009	O
,	O
Valve	O
flew	O
two	O
of	O
the	O
boycott	O
group	O
's	O
most	O
prominent	O
members	O
to	O
Valve	O
,	O
in	O
order	O
to	O
playtest	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
;	O
the	O
two	O
felt	O
that	O
the	O
sequel	O
was	O
well	O
done	O
.	O
</s>
<s>
This	O
event	O
,	O
through	O
a	O
series	O
of	O
correspondences	O
made	O
in	O
jest	O
,	O
shortly	O
led	O
to	O
Valve	O
's	O
Gabe	O
Newell	O
and	O
designer	O
Erik	O
Johnson	O
flying	O
to	O
Australia	O
to	O
visit	O
"	O
Joe	O
W-A	O
"	O
,	O
a	O
Left	B-Application
4	I-Application
Dead	I-Application
modder	O
.	O
</s>
<s>
Newell	O
jokingly	O
reported	O
that	O
Valve	O
was	O
"	O
boycotting	O
"	O
Joe	O
's	O
new	O
mod	O
for	O
the	O
game	O
when	O
Joe	O
asked	O
when	O
he	O
would	O
be	O
flown	O
to	O
Valve	O
in	O
the	O
same	O
manner	O
as	O
the	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
boycotters	O
,	O
but	O
whimsically	O
offered	O
that	O
if	O
Joe	O
was	O
to	O
pay	O
to	O
fly	O
him	O
to	O
the	O
country	O
,	O
he	O
would	O
take	O
a	O
look	O
at	O
it	O
.	O
</s>
<s>
On	O
October	O
14	O
,	O
2009	O
,	O
the	O
initiators	O
of	O
the	O
boycott	O
group	O
announced	O
that	O
they	O
had	O
ended	O
their	O
boycott	O
and	O
were	O
shutting	O
down	O
the	O
40,000	O
-plus	O
group	O
because	O
Valve	O
was	O
retaining	O
their	O
promise	O
of	O
additional	O
content	O
and	O
fixes	O
for	O
Left	B-Application
4	I-Application
Dead	I-Application
,	O
such	O
as	O
the	O
recent	O
release	O
of	O
the	O
"	O
Crash	O
Course	O
"	O
campaign	O
.	O
</s>
<s>
In	O
a	O
video	O
interview	O
posted	O
on	O
October	O
29	O
,	O
2009	O
,	O
Gabe	O
Newell	O
said	O
,	O
"	O
for	O
people	O
who	O
joined	O
the	O
Boycott	O
Group	O
on	O
Steam	B-Application
...	O
they	O
're	O
actually	O
pre-ordering	O
the	O
product	O
at	O
a	O
higher	O
rate	O
than	O
Left	B-Application
4	I-Application
Dead	I-Application
1	I-Application
owners	O
who	O
were	O
n't	O
in	O
the	O
boycott	O
"	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
was	O
refused	O
classification	O
in	O
Australia	O
by	O
the	O
Office	O
of	O
Film	O
and	O
Literature	O
Classification	O
(	O
OFLC	O
)	O
.	O
</s>
<s>
However	O
,	O
a	O
small	O
number	O
of	O
members	O
of	O
the	O
OFLC	O
board	O
believed	O
the	O
game	O
could	O
merit	O
the	O
MA15+	O
rating	O
which	O
was	O
used	O
to	O
publish	O
the	O
first	O
Left	B-Application
4	I-Application
Dead	I-Application
.	O
</s>
<s>
Valve	O
appealed	O
the	O
OFLC	O
's	O
decision	O
about	O
a	O
week	O
after	O
being	O
notified	O
of	O
the	O
ruling	O
,	O
comparing	O
the	O
sequel	O
to	O
its	O
predecessor	B-Application
,	O
which	O
had	O
been	O
classified	O
as	O
MA15+	O
,	O
and	O
the	O
mature	O
ratings	O
the	O
sequel	O
had	O
received	O
from	O
similar	O
rating	O
organizations	O
around	O
the	O
world	O
.	O
</s>
<s>
The	O
Classification	O
Review	O
Board	O
cited	O
"	O
insufficient	O
delineation	O
between	O
the	O
depiction	O
of	O
zombie	B-Application
characters	O
and	O
the	O
human	O
figures	O
"	O
as	O
one	O
of	O
the	O
key	O
factors	O
in	O
its	O
classification	O
refusal	O
.	O
</s>
<s>
Left	B-Application
4	I-Application
Dead	I-Application
2s	I-Application
classification	O
refusal	O
,	O
as	O
well	O
as	O
for	O
other	O
recent	O
games	O
such	O
as	O
Fallout	B-Application
3	I-Application
(	O
has	O
since	O
been	O
rerated	O
MA15+	O
having	O
the	O
same	O
version	O
as	O
other	O
countries	O
)	O
and	O
Aliens	O
vs	O
.	O
</s>
<s>
Following	O
Atkinson	O
's	O
decision	O
to	O
leave	O
the	O
Attorneys	O
General	O
to	O
be	O
replaced	O
by	O
John	O
Rau	O
,	O
who	O
is	O
reportedly	O
in	O
favour	O
of	O
an	O
R18+	O
rating	O
,	O
Valve	O
have	O
revealed	O
that	O
,	O
should	O
the	O
bill	O
be	O
passed	O
,	O
they	O
planned	O
to	O
release	O
an	O
uncensored	O
version	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
for	O
PC	O
in	O
Australia	O
.	O
</s>
<s>
The	O
Australian	O
Federal	O
Parliament	O
passed	O
legislation	O
allowing	O
an	O
R18+	O
classification	O
for	O
video	O
games	O
on	O
January	O
1	O
,	O
2013	O
,	O
and	O
Valve	O
stated	O
they	O
would	O
be	O
exploring	O
legal	O
options	O
of	O
resubmitting	O
the	O
uncensored	O
version	O
of	O
Left	B-Application
4	I-Application
Dead	I-Application
2	I-Application
following	O
this	O
change	O
.	O
</s>
<s>
On	O
August	O
29	O
,	O
2014	O
,	O
the	O
uncensored	O
version	O
was	O
reclassified	O
R18+	O
,	O
effectively	O
unbanning	O
the	O
game	O
,	O
five	O
years	O
after	O
the	O
original	O
release	O
,	O
with	O
Valve	O
adding	O
in	O
the	O
availability	O
to	O
switch	O
to	O
the	O
uncensored	O
version	O
as	O
downloadable	B-Protocol
content	I-Protocol
for	O
users	O
who	O
had	O
purchased	O
the	O
game	O
before	O
the	O
ratings	O
change	O
.	O
</s>
<s>
Users	O
in	O
Germany	O
who	O
had	O
purchased	O
the	O
game	O
,	O
can	O
switch	O
to	O
the	O
uncensored	O
version	O
as	O
downloadable	B-Protocol
content	I-Protocol
,	O
similarly	O
to	O
Australian	O
consumers	O
.	O
</s>
