<s>
Half-Life	B-Application
is	O
a	O
1998	O
first-person	O
shooter	O
(	O
FPS	O
)	O
game	O
developed	O
by	O
Valve	O
and	O
published	O
by	O
Sierra	O
Studios	O
for	O
Windows	O
.	O
</s>
<s>
It	O
was	O
Valve	O
's	O
debut	O
product	O
and	O
the	O
first	O
game	O
in	O
the	O
Half-Life	B-Application
series	O
.	O
</s>
<s>
Players	O
assume	O
the	O
role	O
of	O
Gordon	O
Freeman	O
,	O
a	O
scientist	O
who	O
must	O
escape	O
the	O
Black	B-Application
Mesa	I-Application
Research	O
Facility	O
after	O
it	O
is	O
invaded	O
by	O
aliens	O
.	O
</s>
<s>
Valve	O
developed	O
it	O
using	O
GoldSrc	B-Application
,	O
a	O
heavily	O
modified	O
version	O
of	O
the	O
Quake	B-Application
engine	I-Application
,	O
licensed	O
from	O
id	O
Software	O
.	O
</s>
<s>
Half-Life	B-Application
received	O
acclaim	O
for	O
its	O
graphics	O
,	O
gameplay	O
and	O
narrative	O
,	O
and	O
won	O
more	O
than	O
50	O
PC	O
"	O
Game	O
of	O
the	O
Year	O
"	O
awards	O
.	O
</s>
<s>
It	O
was	O
followed	O
by	O
the	O
expansion	O
packs	O
Opposing	B-Application
Force	I-Application
(	O
1999	O
)	O
and	O
Blue	B-Application
Shift	I-Application
(	O
2001	O
)	O
,	O
developed	O
by	O
Gearbox	O
Software	O
.	O
</s>
<s>
It	O
was	O
ported	O
to	O
the	O
PlayStation	B-Device
2	I-Device
in	O
2001	O
,	O
along	O
with	O
the	O
multiplayer	O
expansion	O
Decay	B-Application
,	O
and	O
to	O
OS	B-Operating_System
X	I-Operating_System
and	O
Linux	B-Application
in	O
2013	O
.	O
</s>
<s>
Valve	O
ported	O
Half-Life	B-Application
to	O
its	O
Source	B-Application
engine	I-Application
as	O
Half-Life	B-Application
:	O
Source	B-Application
in	O
2004	O
.	O
</s>
<s>
In	O
2020	O
,	O
Crowbar	B-Application
Collective	I-Application
released	O
an	O
unofficial	O
remake	O
,	O
Black	B-Application
Mesa	I-Application
.	O
</s>
<s>
Half-Life	B-Application
inspired	O
numerous	O
fan-made	O
mods	O
,	O
some	O
of	O
which	O
became	O
standalone	O
games	O
,	O
such	O
as	O
Counter-Strike	B-Application
,	O
Day	B-Application
of	I-Application
Defeat	I-Application
,	O
and	O
Sven	B-Application
Co-op	I-Application
.	O
</s>
<s>
It	O
was	O
followed	O
by	O
Half-Life	B-Application
2	I-Application
(	O
2004	O
)	O
,	O
Half-Life	B-Application
2	I-Application
:	I-Application
Episode	I-Application
One	I-Application
(	O
2006	O
)	O
,	O
Half-Life	B-Application
2	I-Application
:	I-Application
Episode	I-Application
Two	I-Application
(	O
2007	O
)	O
,	O
and	O
Half-Life	B-Application
:	I-Application
Alyx	I-Application
(	O
2020	O
)	O
.	O
</s>
<s>
Half-Life	B-Application
is	O
a	O
first-person	O
shooter	O
(	O
FPS	O
)	O
that	O
requires	O
the	O
player	O
to	O
perform	O
combat	O
tasks	O
and	O
puzzle	O
solving	O
to	O
advance	O
through	O
the	O
game	O
.	O
</s>
<s>
Unlike	O
most	O
of	O
its	O
peers	O
at	O
the	O
time	O
,	O
Half-Life	B-Application
uses	O
scripted	O
sequences	O
,	O
such	O
as	O
a	O
Vortigaunt	O
ramming	O
down	O
a	O
door	O
,	O
to	O
advance	O
major	O
plot	O
points	O
.	O
</s>
<s>
Half-Life	B-Application
has	O
no	O
levels	O
;	O
it	O
instead	O
divides	O
the	O
game	O
into	O
chapters	O
,	O
whose	O
titles	O
briefly	O
appear	O
on	O
screen	O
as	O
the	O
player	O
progresses	O
through	O
the	O
game	O
.	O
</s>
<s>
Progress	O
through	O
the	O
world	O
is	O
continuous	O
,	O
(	O
except	O
for	O
short	O
loading	O
pauses	O
)	O
with	O
each	O
map	O
of	O
the	O
game	O
connecting	O
directly	O
to	O
the	O
next	O
,	O
with	O
the	O
exception	O
of	O
levels	O
involving	O
teleportation	B-General_Concept
.	O
</s>
<s>
Some	O
puzzles	O
involve	O
using	O
the	O
environment	O
to	O
kill	O
an	O
enemy	O
,	O
like	O
turning	O
a	O
valve	O
to	O
spray	O
hot	O
steam	B-Application
at	O
their	O
enemies	O
.	O
</s>
<s>
Half-Life	B-Application
includes	O
online	O
multiplayer	O
support	O
for	O
both	O
individual	O
and	O
team-based	O
deathmatch	O
modes	O
.	O
</s>
<s>
Theoretical	O
physicist	O
Gordon	O
Freeman	O
arrives	O
late	O
for	O
work	O
at	O
the	O
Black	B-Application
Mesa	I-Application
Research	O
Facility	O
.	O
</s>
<s>
Surviving	O
scientists	O
urge	O
Gordon	O
to	O
head	O
to	O
the	O
surface	O
,	O
where	O
he	O
defends	O
himself	O
against	O
hostile	O
Xen	O
creatures	O
and	O
the	O
Hazardous	O
Environment	O
Combat	O
Unit	O
(	O
HECU	O
)	O
,	O
a	O
special	O
unit	O
of	O
United	O
States	O
Marine	O
Corps	O
sent	O
to	O
cover	O
up	O
the	O
incident	O
by	O
killing	O
all	O
of	O
the	O
aliens	O
and	O
any	O
Black	B-Application
Mesa	I-Application
personnel	O
they	O
find	O
.	O
</s>
<s>
Heading	O
to	O
the	O
surface	O
,	O
Gordon	O
learns	O
that	O
scientists	O
from	O
the	O
Lambda	B-General_Concept
Complex	O
may	O
have	O
found	O
a	O
way	O
to	O
close	O
the	O
portal	O
.	O
</s>
<s>
Overwhelmed	O
by	O
the	O
alien	O
forces	O
,	O
the	O
HECU	O
Marines	O
pull	O
out	O
of	O
Black	B-Application
Mesa	I-Application
and	O
begin	O
airstrikes	B-Application
.	O
</s>
<s>
Scaling	O
cliffs	O
,	O
navigating	O
destroyed	O
buildings	O
,	O
and	O
traversing	O
through	O
underground	O
water	O
channels	O
,	O
Gordon	O
arrives	O
at	O
the	O
Lambda	B-General_Concept
Complex	O
,	O
where	O
scientists	O
learn	O
the	O
portal	O
is	O
being	O
forced	O
open	O
on	O
the	O
other	O
side	O
by	O
a	O
mighty	O
entity	O
.	O
</s>
<s>
They	O
have	O
developed	O
teleportation	B-General_Concept
technology	O
that	O
allows	O
Gordon	O
to	O
travel	O
to	O
Xen	O
,	O
where	O
he	O
is	O
tasked	O
with	O
stopping	O
the	O
entity	O
.	O
</s>
<s>
Gordon	O
is	O
summoned	O
by	O
the	O
mysterious	O
G-Man	O
,	O
who	O
has	O
been	O
watching	O
his	O
progress	O
in	O
Black	B-Application
Mesa	I-Application
.	O
</s>
<s>
For	O
its	O
first	O
product	O
,	O
Valve	O
settled	O
on	O
a	O
concept	O
for	O
a	O
horror	O
first-person	O
shooter	O
(	O
FPS	O
)	O
game	O
using	O
the	O
Quake	B-Application
engine	I-Application
licensed	O
from	O
id	O
Software	O
.	O
</s>
<s>
They	O
also	O
licensed	O
the	O
Quake	B-Application
II	I-Application
engine	I-Application
,	O
and	O
combined	O
code	O
from	O
both	O
engines	O
with	O
their	O
own	O
,	O
adding	O
skeletal	O
animation	O
and	O
Direct3D	B-Application
support	O
;	O
Newell	O
estimated	O
that	O
around	O
75%	O
of	O
the	O
final	O
engine	O
code	O
was	O
by	O
Valve	O
.	O
</s>
<s>
As	O
the	O
project	O
expanded	O
,	O
Valve	O
cancelled	O
development	O
of	O
a	O
fantasy	O
role-playing	O
game	O
,	O
Prospero	O
,	O
and	O
the	O
Prospero	O
team	O
joined	O
the	O
Half-Life	B-Application
project	O
.	O
</s>
<s>
Half-Life	B-Application
was	O
inspired	O
by	O
FPS	O
games	O
Doom	B-Application
(	O
1993	O
)	O
and	O
Quake	B-Application
(	O
1996	O
)	O
,	O
Stephen	O
King	O
's	O
1980	O
novella	O
The	O
Mist	O
,	O
and	O
a	O
1963	O
episode	O
of	O
The	O
Outer	O
Limits	O
titled	O
"	O
The	O
Borderland	O
"	O
.	O
</s>
<s>
According	O
to	O
the	O
designer	O
Harry	O
Teasley	O
,	O
Doom	B-Application
was	O
a	O
major	O
influence	O
,	O
and	O
the	O
team	O
wanted	O
Half-Life	B-Application
to	O
"	O
scare	O
you	O
like	O
Doom	B-Application
did	O
"	O
.	O
</s>
<s>
The	O
name	O
Half-Life	B-Application
was	O
chosen	O
because	O
it	O
was	O
evocative	O
of	O
the	O
theme	O
,	O
not	O
clichéd	O
,	O
and	O
had	O
a	O
corresponding	O
visual	O
symbol	O
:	O
the	O
Greek	O
letter	O
λ	O
(	O
lower-case	O
lambda	B-General_Concept
)	O
,	O
which	O
represents	O
the	O
decay	B-Application
constant	O
in	O
the	O
half-life	B-Application
equation	O
.	O
</s>
<s>
Sierra	O
On-Line	O
signed	O
Valve	O
for	O
a	O
one-game	O
deal	O
as	O
it	O
was	O
interested	O
in	O
making	O
a	O
3D	O
action	O
game	O
,	O
especially	O
one	O
based	O
on	O
the	O
Quake	B-Application
engine	I-Application
.	O
</s>
<s>
Valve	O
first	O
showed	O
Half-Life	B-Application
in	O
early	O
1997	O
;	O
it	O
was	O
a	O
success	O
at	O
E3	O
that	O
year	O
,	O
where	O
Valve	O
demonstrated	O
the	O
animation	O
and	O
artificial	B-Application
intelligence	I-Application
.	O
</s>
<s>
Novel	O
features	O
of	O
the	O
artificial	B-Application
intelligence	I-Application
included	O
fear	O
and	O
pack	O
behavior	O
.	O
</s>
<s>
Valve	O
aimed	O
for	O
a	O
November	O
1997	O
release	O
to	O
compete	O
with	O
Quake	B-Application
II	I-Application
.	O
</s>
<s>
When	O
the	O
rest	O
of	O
the	O
team	O
played	O
the	O
level	O
,	O
which	O
the	O
designer	O
Ken	O
Birdwell	O
described	O
as	O
"	O
Die	B-Application
Hard	I-Application
meets	O
Evil	B-Application
Dead	I-Application
"	O
,	O
they	O
agreed	O
to	O
use	O
it	O
as	O
a	O
baseline	O
.	O
</s>
<s>
An	O
early	O
version	O
of	O
Half-Life	B-Application
began	O
immediately	O
after	O
the	O
disaster	O
,	O
with	O
the	O
environments	O
already	O
wrecked	O
.	O
</s>
<s>
Birdwell	O
said	O
that	O
while	O
there	O
were	O
struggles	O
at	O
first	O
,	O
the	O
cabal	O
approach	O
was	O
critical	O
for	O
Half-Lifes	O
success	O
,	O
and	O
was	O
reused	O
for	O
Team	B-Application
Fortress	I-Application
2	I-Application
from	O
the	O
start	O
.	O
</s>
<s>
Much	O
of	O
the	O
detail	O
of	O
Half-Life	B-Application
development	O
has	O
been	O
lost	O
.	O
</s>
<s>
According	O
to	O
the	O
Valve	O
employee	O
Erik	O
Johnson	O
,	O
two	O
or	O
three	O
months	O
before	O
release	O
,	O
their	O
Visual	B-Protocol
SourceSafe	I-Protocol
source	B-Application
control	O
system	O
"	O
exploded	O
"	O
.	O
</s>
<s>
Half-Life	B-Application
saw	O
fervent	O
support	O
from	O
independent	O
game	O
developers	O
,	O
due	O
in	O
no	O
small	O
part	O
to	O
support	O
and	O
encouragement	O
from	O
Valve	O
.	O
</s>
<s>
Worldcraft	B-Application
,	O
the	O
level-design	O
tool	O
used	O
during	O
the	O
game	O
's	O
development	O
,	O
was	O
included	O
with	O
the	O
game	O
software	O
.	O
</s>
<s>
Printed	O
materials	O
accompanying	O
the	O
game	O
indicated	O
Worldcraft	B-Application
's	O
eventual	O
release	O
as	O
a	O
retail	O
product	O
,	O
but	O
those	O
plans	O
never	O
materialized	O
.	O
</s>
<s>
Valve	O
also	O
released	O
a	O
software	B-Application
development	I-Application
kit	I-Application
,	O
enabling	O
developers	O
to	O
modify	O
the	O
game	O
and	O
create	O
mods	O
.	O
</s>
<s>
Supporting	O
tools	O
(	O
including	O
texture	O
editors	O
,	O
model	O
editors	O
,	O
and	O
level	O
editors	O
such	O
as	O
the	O
multiple	O
engine	O
editor	O
QuArK	B-Language
)	O
were	O
either	O
created	O
or	O
updated	O
to	O
work	O
with	O
Half-Life	B-Application
.	O
</s>
<s>
The	O
Half-Life	B-Application
software	B-Application
development	I-Application
kit	I-Application
served	O
as	O
the	O
development	O
base	O
for	O
many	O
mods	O
,	O
including	O
the	O
Valve-developed	O
Team	B-Application
Fortress	I-Application
Classic	I-Application
and	O
Deathmatch	O
Classic	O
(	O
a	O
remake	O
of	O
Quakes	B-Application
multiplayer	O
deathmatch	O
mode	O
in	O
the	O
GoldSrc	B-Application
engine	I-Application
)	O
.	O
</s>
<s>
Other	O
mods	O
such	O
as	O
Counter-Strike	B-Application
and	O
Day	B-Application
of	I-Application
Defeat	I-Application
(	O
DOD	O
)	O
began	O
life	O
as	O
the	O
work	O
of	O
independent	O
developers	O
who	O
later	O
received	O
aid	O
from	O
Valve	O
.	O
</s>
<s>
Other	O
multiplayer	O
mods	O
include	O
Action	B-Application
Half-Life	I-Application
,	O
Firearms	B-Application
,	O
Science	O
and	O
Industry	O
,	O
The	O
Specialists	O
,	O
Pirates	B-Application
,	I-Application
Vikings	I-Application
and	I-Application
Knights	I-Application
,	O
Natural	B-Application
Selection	I-Application
and	O
Sven	B-Application
Co-op	I-Application
.	O
</s>
<s>
Numerous	O
single-player	O
mods	O
have	O
also	O
been	O
created	O
,	O
include	O
USS	O
Darkstar	O
(	O
1999	O
,	O
a	O
futuristic	O
action-adventure	O
on	O
board	O
a	O
zoological	O
research	O
spaceship	O
)	O
,	O
They	O
Hunger	O
(	O
2000	O
–	O
2001	O
,	O
a	O
survival	O
horror	O
total	O
conversion	O
trilogy	O
involving	O
zombies	O
)	O
,	O
Poke646	O
(	O
2001	O
,	O
a	O
follow-up	O
to	O
the	O
original	O
Half-Life	B-Application
story	O
with	O
improved	O
graphics	O
)	O
,	O
and	O
Someplace	B-Application
Else	I-Application
(	O
2002	O
,	O
a	O
side-story	O
to	O
the	O
original	O
Half-Life	B-Application
)	O
.	O
</s>
<s>
Among	O
the	O
stolen	O
files	O
were	O
the	O
unreleased	O
Half-Life	B-Application
modification	O
Half-Life	B-Application
:	O
Threewave	O
,	O
a	O
canceled	O
remake	O
of	O
the	O
mod	O
Threewave	O
CTF	O
from	O
Quake	B-Application
.	O
</s>
<s>
The	O
files	O
were	O
later	O
found	O
by	O
independent	O
reporter	O
Tyler	O
McVicker	O
of	O
Valve	O
News	O
Network	O
on	O
a	O
Vietnamese	O
FTP	B-Protocol
server	I-Protocol
in	O
February	O
2016	O
,	O
and	O
were	O
unofficially	O
released	O
in	O
September	O
2016	O
.	O
</s>
<s>
Some	O
Half-Life	B-Application
modifications	O
received	O
retail	O
releases	O
.	O
</s>
<s>
Counter-Strike	B-Application
was	O
the	O
most	O
successful	O
,	O
having	O
been	O
released	O
in	O
six	O
different	O
editions	O
:	O
as	O
a	O
standalone	O
product	O
(	O
2000	O
)	O
,	O
as	O
part	O
of	O
the	O
Platinum	O
Pack	O
(	O
2000	O
)	O
,	O
as	O
an	O
Xbox	B-Application
version	O
(	O
2003	O
)	O
,	O
and	O
as	O
a	O
single-player	O
spin-off	O
,	O
Counter-Strike	B-Application
:	I-Application
Condition	I-Application
Zero	I-Application
(	O
2004	O
)	O
,	O
as	O
well	O
as	O
in	O
two	O
versions	O
using	O
the	O
Source	B-Application
engine	I-Application
.	O
</s>
<s>
Team	B-Application
Fortress	I-Application
Classic	I-Application
,	O
Day	B-Application
of	I-Application
Defeat	I-Application
,	O
Gunman	B-Application
Chronicles	I-Application
(	O
2000	O
,	O
a	O
futuristic	O
Western	O
movie-style	O
total	O
conversion	O
with	O
emphasis	O
on	O
its	O
single-player	O
mode	O
)	O
and	O
Sven	B-Application
Co-op	I-Application
were	O
also	O
released	O
as	O
standalone	O
products	O
.	O
</s>
<s>
Half-Life	B-Application
is	O
also	O
the	O
subject	O
of	O
the	O
YouTube	B-General_Concept
improv	O
roleplaying	O
series	O
Half-Life	B-Application
VR	O
but	O
the	O
AI	O
is	O
Self-Aware	O
and	O
Freeman	O
's	O
Mind	O
.	O
</s>
<s>
Half-Life	B-Application
was	O
released	O
in	O
November	O
1998	O
.	O
</s>
<s>
The	O
revised	O
version	O
of	O
Half-Life	B-Application
shown	O
at	O
E3	O
1998	O
was	O
given	O
Game	O
Critics	O
Awards	O
for	O
"	O
Best	O
PC	O
Game	O
"	O
and	O
"	O
Best	O
Action	O
Game	O
"	O
.	O
</s>
<s>
Valve	O
released	O
two	O
demos	O
for	O
Half-Life	B-Application
.	O
</s>
<s>
The	O
first	O
,	O
Half-Life	B-Application
:	I-Application
Day	I-Application
One	I-Application
,	O
contained	O
the	O
first	O
fifth	O
of	O
the	O
game	O
and	O
was	O
distributed	O
with	O
certain	O
graphic	O
cards	O
.	O
</s>
<s>
The	O
second	O
demo	O
,	O
Half-Life	B-Application
:	O
Uplink	O
,	O
was	O
released	O
on	O
February	O
12	O
,	O
1999	O
,	O
and	O
featured	O
original	O
content	O
.	O
</s>
<s>
A	O
short	O
film	O
based	O
on	O
Half-Life	B-Application
,	O
also	O
titled	O
Half-Life	B-Application
:	O
Uplink	O
,	O
was	O
developed	O
by	O
Cruise	O
Control	O
,	O
a	O
British	O
marketing	O
agency	O
,	O
and	O
released	O
on	O
February	O
11	O
,	O
1999	O
.	O
</s>
<s>
The	O
film	O
's	O
protagonist	O
is	O
a	O
journalist	O
who	O
infiltrates	O
the	O
Black	B-Application
Mesa	I-Application
Research	O
Facility	O
,	O
trying	O
to	O
discover	O
what	O
has	O
happened	O
there	O
.	O
</s>
<s>
Half-Life	B-Application
was	O
censored	O
in	O
Germany	O
to	O
comply	O
with	O
the	O
Federal	O
Department	O
for	O
Media	O
Harmful	O
to	O
Young	O
Persons	O
(	O
BPjM	O
by	O
its	O
German	O
abbreviation	O
)	O
,	O
which	O
regulates	O
depictions	O
of	O
violence	O
against	O
humans	O
.	O
</s>
<s>
In	O
2017	O
,	O
BPjM	O
removed	O
Half-Life	B-Application
from	O
its	O
list	O
;	O
to	O
acknowledge	O
this	O
,	O
Valve	O
released	O
Half-Life	B-Application
Uncensored	O
,	O
a	O
free	O
downloadable	B-Protocol
content	I-Protocol
pack	O
,	O
that	O
reverts	O
the	O
censorship	O
.	O
</s>
<s>
Captivation	O
Digital	O
Laboratories	O
and	O
Gearbox	O
Software	O
developed	O
a	O
port	O
of	O
Half-Life	B-Application
for	O
the	B-Operating_System
Dreamcast	I-Operating_System
,	O
with	O
new	O
character	O
models	O
and	O
textures	O
and	O
an	O
exclusive	O
expansion	O
,	O
Blue	B-Application
Shift	I-Application
.	O
</s>
<s>
Following	O
the	O
cancellations	O
of	O
several	O
third-party	O
Dreamcast	B-Operating_System
games	O
in	O
the	O
wake	O
of	O
Sega	O
's	O
decision	O
to	O
discontinue	O
the	O
console	O
in	O
March	O
2001	O
,	O
Sierra	O
cancelled	O
the	O
port	O
weeks	O
before	O
its	O
scheduled	O
release	O
in	O
June	O
,	O
citing	O
"	O
changing	O
marketing	O
conditions	O
"	O
.	O
</s>
<s>
Blue	B-Application
Shift	I-Application
was	O
ported	O
to	O
Windows	O
.	O
</s>
<s>
The	B-Operating_System
Dreamcast	I-Operating_System
port	O
became	O
the	O
basis	O
of	O
the	O
Half-Life	B-Application
port	O
for	O
PlayStation	B-Device
2	I-Device
,	O
released	O
in	O
late	O
2001	O
.	O
</s>
<s>
This	O
version	O
added	O
competitive	O
play	O
and	O
a	O
co-op	O
expansion	O
,	O
Half-Life	B-Application
:	I-Application
Decay	I-Application
.	O
</s>
<s>
Valve	O
canceled	O
a	O
version	O
of	O
Half-Life	B-Application
for	O
Mac	B-Application
,	O
developed	O
by	O
Logicware	O
,	O
in	O
2000	O
.	O
</s>
<s>
Newell	O
said	O
the	O
port	O
was	O
substandard	O
and	O
would	O
have	O
made	O
Mac	B-Application
players	O
"	O
second-class	O
customers	O
"	O
.	O
</s>
<s>
Valve	O
released	O
ports	O
for	O
OS	B-Operating_System
X	I-Operating_System
and	O
Linux	B-Application
in	O
2013	O
.	O
</s>
<s>
In	O
2004	O
,	O
Valve	O
released	O
Half-Life	B-Application
:	O
Source	B-Application
,	O
a	O
version	O
of	O
Half-Life	B-Application
created	O
in	O
their	O
new	O
game	O
engine	O
,	O
Source	B-Application
.	O
</s>
<s>
Black	B-Application
Mesa	I-Application
,	O
a	O
third-party	O
remake	O
of	O
Half-Life	B-Application
developed	O
by	O
Crowbar	B-Application
Collective	I-Application
in	O
the	O
Source	B-Application
engine	I-Application
,	O
was	O
published	O
as	O
a	O
free	O
mod	O
in	O
September	O
2012	O
and	O
later	O
approved	O
by	O
Valve	O
for	O
a	O
commercial	O
release	O
.	O
</s>
<s>
Half-Life	B-Application
was	O
followed	O
by	O
an	O
expansion	O
pack	O
,	O
Opposing	B-Application
Force	I-Application
,	O
on	O
November	O
1	O
,	O
1999	O
,	O
developed	O
by	O
Gearbox	O
Software	O
.	O
</s>
<s>
Gearbox	O
developed	O
a	O
second	O
expansion	O
pack	O
,	O
Blue	B-Application
Shift	I-Application
,	O
in	O
which	O
players	O
control	O
Barney	O
Calhoun	O
,	O
a	O
security	O
guard	O
at	O
Black	B-Application
Mesa	I-Application
,	O
as	O
he	O
attempts	O
to	O
escape	O
the	O
facility	O
.	O
</s>
<s>
It	O
was	O
developed	O
as	O
a	O
bonus	O
campaign	O
for	O
the	B-Operating_System
Dreamcast	I-Operating_System
port	O
of	O
Half-Life	B-Application
;	O
but	O
released	O
for	O
Windows	O
on	O
June	O
12	O
,	O
2001	O
,	O
after	O
the	O
port	O
was	O
canceled	O
.	O
</s>
<s>
Gearbox	O
created	O
a	O
cooperative	O
multiplayer	O
expansion	O
pack	O
,	O
Decay	B-Application
,	O
exclusively	O
for	O
the	O
PlayStation	B-Device
2	I-Device
port	O
of	O
Half-Life	B-Application
.	O
</s>
<s>
Half-Life	B-Application
has	O
a	O
score	O
of	O
96	O
out	O
of	O
100	O
on	O
aggregate	O
review	O
website	O
Metacritic	O
.	O
</s>
<s>
It	O
's	O
one	O
of	O
the	O
best	O
games	O
of	O
any	O
year	O
,	O
an	O
instant	O
classic	O
that	O
is	O
miles	O
better	O
than	O
any	O
of	O
its	O
immediate	O
competition	O
,	O
and	O
–	O
in	O
its	O
single-player	O
form	O
–	O
is	O
the	O
best	O
shooter	O
since	O
the	O
original	O
Doom	B-Application
"	O
.	O
</s>
<s>
AllGame	O
said	O
,	O
"	O
It	O
is	O
n't	O
everyday	O
that	O
you	O
come	O
across	O
a	O
game	O
that	O
totally	O
revolutionizes	O
an	O
entire	O
genre	O
,	O
but	O
Half-Life	B-Application
has	O
done	O
just	O
that.	O
"	O
</s>
<s>
The	O
Electric	O
Playground	O
said	O
that	O
Half-Life	B-Application
was	O
an	O
"	O
immersive	O
and	O
engaging	O
entertainment	O
experience	O
"	O
,	O
but	O
noted	O
that	O
this	O
only	O
lasted	O
for	O
the	O
first	O
half	O
of	O
the	O
game	O
,	O
explaining	O
that	O
the	O
game	O
"	O
peaked	O
too	O
soon	O
"	O
.	O
</s>
<s>
The	O
GoldSrc	B-Application
engine	I-Application
did	O
not	O
provide	O
as	O
much	O
precise	O
control	O
for	O
the	O
player	O
during	O
jumping	O
,	O
making	O
these	O
jumps	O
difficult	O
and	O
often	O
with	O
Freeman	O
falling	O
into	O
a	O
void	O
and	O
the	O
player	O
restarting	O
the	O
game	O
.	O
</s>
<s>
Awards	O
)	O
,	O
Half-Life	B-Application
won	O
the	O
awards	O
for	O
"	O
Computer	O
Game	O
of	O
the	O
Year	O
"	O
and	O
"	O
Computer	O
Action	O
Game	O
of	O
the	O
Year	O
"	O
,	O
along	O
with	O
nominations	O
for	O
"	O
Game	O
of	O
the	O
Year	O
"	O
,	O
"	O
Outstanding	O
Achievement	O
in	O
Art/Graphics	O
"	O
,	O
"	O
Outstanding	O
Achievement	O
in	O
Character	O
or	O
Story	O
Development	O
"	O
,	O
"	O
Outstanding	O
Achievement	O
in	O
Interactive	O
Design	O
"	O
and	O
"	O
Outstanding	O
Achievement	O
in	O
Software	O
Engineering	O
"	O
.	O
</s>
<s>
Jeff	O
Lundrigan	O
reviewed	O
the	O
PlayStation	B-Device
2	I-Device
version	O
of	O
the	O
game	O
for	O
Next	O
Generation	O
,	O
rating	O
it	O
three	O
stars	O
out	O
of	O
five	O
,	O
and	O
stated	O
that	O
"	O
It	O
may	O
be	O
getting	O
old	O
,	O
but	O
there	O
's	O
still	O
a	O
surprising	O
amount	O
of	O
life	O
in	O
Half-Life	B-Application
"	O
.	O
</s>
<s>
the	O
PlayStation	B-Device
2	I-Device
version	O
of	O
Half-Life	B-Application
was	O
a	O
nominee	O
for	O
The	O
Electric	O
Playgrounds	O
2001	O
Blister	O
Awards	O
for	O
"	O
Best	O
Console	O
Shooter	O
Game	O
"	O
,	O
but	O
lost	O
to	O
Halo	O
:	O
Combat	O
Evolved	O
for	O
Xbox	B-Application
.	O
</s>
<s>
In	O
the	O
November	O
1999	O
,	O
October	O
2001	O
,	O
and	O
April	O
2005	O
issues	O
of	O
PC	O
Gamer	O
,	O
Half-Life	B-Application
was	O
named	O
the	O
best	O
PC	O
game	O
of	O
all	O
time	O
.	O
</s>
<s>
In	O
2004	O
,	O
GameSpy	O
readers	O
voted	O
Half-Life	B-Application
the	O
best	O
game	O
of	O
all	O
time	O
.	O
</s>
<s>
GameSpot	O
inducted	O
Half-Life	B-Application
into	O
their	O
Greatest	O
Games	O
of	O
All	O
Time	O
list	O
in	O
May	O
2007	O
.	O
</s>
<s>
In	O
2007	O
,	O
IGN	O
described	O
Half-Life	B-Application
as	O
one	O
of	O
the	O
most	O
influential	O
video	O
games	O
,	O
and	O
in	O
2013	O
wrote	O
that	O
the	O
history	O
of	O
the	O
FPS	O
genre	O
"	O
breaks	O
down	O
pretty	O
cleanly	O
into	O
pre-Half-Life	O
and	O
post-Half-Life	O
eras	O
"	O
.	O
</s>
<s>
In	O
2021	O
,	O
the	O
Guardian	O
ranked	O
Half-Life	B-Application
the	O
third-greatest	O
game	O
of	O
the	O
1990s	O
,	O
writing	O
that	O
it	O
"	O
helped	O
write	O
the	O
rulebook	O
for	O
how	O
games	O
tell	O
their	O
stories	O
without	O
resorting	O
to	O
aping	O
the	O
conventions	O
of	O
film	O
"	O
.	O
</s>
<s>
According	O
to	O
Newell	O
,	O
Half-Life	B-Application
was	O
budgeted	O
with	O
the	O
expectation	O
of	O
lifetime	O
sales	O
of	O
around	O
180,000	O
copies	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
Half-Life	B-Application
debuted	O
at	O
#8	O
on	O
PC	O
Data	O
's	O
weekly	O
PC	O
game	O
sales	O
chart	O
for	O
the	O
November	O
15	O
–	O
21	O
period	O
,	O
with	O
an	O
average	O
retail	O
price	O
(	O
ARP	O
)	O
of	O
$49	O
.	O
</s>
<s>
PC	O
Data	O
declared	O
Half-Life	B-Application
November	O
's	O
sixth-best-selling	O
PC	O
game	O
in	O
the	O
United	O
States	O
,	O
a	O
position	O
it	O
held	O
for	O
the	O
month	O
of	O
December	O
.	O
</s>
<s>
In	O
January	O
1999	O
,	O
Half-Life	B-Application
debuted	O
at	O
#3	O
on	O
Chart-Track	O
'	O
s	O
PC	O
game	O
sales	O
rankings	O
for	O
the	O
United	O
Kingdom	O
,	O
and	O
remained	O
in	O
PC	O
Data	O
's	O
weekly	O
top	O
10	O
for	O
the	O
entire	O
month	O
,	O
peaking	O
at	O
#4	O
.	O
</s>
<s>
By	O
January	O
19	O
,	O
after	O
two	O
full	O
months	O
of	O
availability	O
,	O
global	O
sales	O
of	O
Half-Life	B-Application
surpassed	O
500,000	O
units	O
.	O
</s>
<s>
In	O
the	O
United	O
Kingdom	O
,	O
it	O
placed	O
second	O
in	O
February	O
—	O
behind	O
the	O
debut	O
of	O
Baldur	B-Application
's	I-Application
Gate	I-Application
—	O
and	O
fifth	O
in	O
March	O
.	O
</s>
<s>
On	O
April	O
23	O
,	O
Sierra	O
announced	O
that	O
global	O
sales	O
of	O
Half-Life	B-Application
had	O
reached	O
almost	O
1	O
million	O
copies	O
.	O
</s>
<s>
After	O
maintaining	O
the	O
16th	O
place	O
for	O
May	O
in	O
the	O
US	O
,	O
Half-Life	B-Application
exited	O
PC	O
Data	O
's	O
monthly	O
top	O
20	O
in	O
June	O
.	O
</s>
<s>
Half-Life	B-Application
became	O
the	O
fifth-bestselling	O
PC	O
game	O
of	O
the	O
first	O
half	O
of	O
1999	O
in	O
the	O
US	O
.	O
</s>
<s>
The	O
PlayStation	B-Device
2	I-Device
version	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>
Guinness	O
World	O
Records	O
awarded	O
Half-Life	B-Application
the	O
world	O
record	O
for	O
Best-Selling	O
First-Person	O
Shooter	O
of	O
All	O
Time	O
(	O
PC	O
)	O
in	O
the	O
Guinness	O
World	O
Records	O
:	O
Gamer	O
's	O
Edition	O
2008	O
.	O
</s>
<s>
Half-Life	B-Application
2	I-Application
was	O
announced	O
at	O
E3	O
2003	O
and	O
released	O
in	O
2004	O
.	O
</s>
<s>
The	O
player	O
controls	O
Freeman	O
20	O
years	O
after	O
the	O
Black	B-Application
Mesa	I-Application
incident	O
in	O
the	O
dystopian	O
City	O
17	O
,	O
where	O
he	O
joins	O
a	O
rebellion	O
against	O
an	O
alien	O
regime	O
.	O
</s>
<s>
It	O
was	O
followed	O
by	O
the	O
episodic	O
games	O
Half-Life	B-Application
2	I-Application
:	I-Application
Episode	I-Application
One	I-Application
(	O
2006	O
)	O
and	O
Half-Life	B-Application
2	I-Application
:	I-Application
Episode	I-Application
Two	I-Application
(	O
2007	O
)	O
.	O
</s>
<s>
After	O
cancelling	O
several	O
other	O
Half-Life	B-Application
projects	O
,	O
Valve	O
released	O
Half-Life	B-Application
:	I-Application
Alyx	I-Application
in	O
2020	O
.	O
</s>
