<s>
Portal	B-Application
is	O
a	O
2007	O
puzzle-platform	O
game	O
developed	O
and	O
published	O
by	O
Valve	O
.	O
</s>
<s>
It	O
was	O
released	O
in	O
a	O
bundle	O
,	O
The	B-Application
Orange	I-Application
Box	I-Application
,	O
for	O
Windows	O
,	O
Xbox	B-Operating_System
360	I-Operating_System
and	O
PlayStation	B-Operating_System
3	I-Operating_System
,	O
and	O
has	O
been	O
since	O
ported	O
to	O
other	O
systems	O
,	O
including	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Linux	B-Application
,	O
Android	B-Application
(	O
via	O
Nvidia	B-Application
Shield	I-Application
)	O
,	O
and	O
Nintendo	B-Application
Switch	I-Application
.	O
</s>
<s>
Portal	B-Application
consists	O
primarily	O
of	O
a	O
series	O
of	O
puzzles	O
that	O
must	O
be	O
solved	O
by	O
teleporting	O
the	O
player	O
's	O
character	O
and	O
simple	O
objects	O
using	O
"	O
the	O
Aperture	O
Science	O
Handheld	O
Portal	B-Application
Device	O
"	O
,	O
often	O
referred	O
to	O
as	O
the	O
"	O
portal	B-Application
gun	O
"	O
,	O
a	O
device	O
that	O
can	O
create	O
inter-spatial	O
portals	B-Application
between	O
two	O
flat	O
planes	O
.	O
</s>
<s>
The	O
player-character	O
,	O
Chell	O
,	O
is	O
challenged	O
and	O
taunted	O
by	O
an	O
artificial	B-Application
intelligence	I-Application
named	O
GLaDOS	O
(	O
Genetic	O
Lifeform	O
and	O
Disk	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
)	O
to	O
complete	O
each	O
puzzle	O
in	O
the	O
Aperture	O
Science	O
Enrichment	O
Center	O
using	O
the	O
portal	B-Application
gun	O
with	O
the	O
promise	O
of	O
receiving	O
cake	O
when	O
all	O
the	O
puzzles	O
are	O
completed	O
.	O
</s>
<s>
The	O
game	O
's	O
unique	O
physics	O
allows	O
kinetic	O
energy	O
to	O
be	O
retained	O
through	O
portals	B-Application
,	O
requiring	O
creative	O
use	O
of	O
portals	B-Application
to	O
maneuver	O
through	O
the	O
test	O
chambers	O
.	O
</s>
<s>
This	O
gameplay	O
element	O
is	O
based	O
on	O
a	O
similar	O
concept	O
from	O
the	O
game	O
Narbacular	B-Application
Drop	I-Application
;	O
many	O
of	O
the	O
team	O
members	O
from	O
the	O
DigiPen	O
Institute	O
of	O
Technology	O
who	O
worked	O
on	O
Narbacular	B-Application
Drop	I-Application
were	O
hired	O
by	O
Valve	O
for	O
the	O
creation	O
of	O
Portal	B-Application
,	O
making	O
it	O
a	O
spiritual	O
successor	O
to	O
the	O
game	O
.	O
</s>
<s>
Portal	B-Application
was	O
acclaimed	O
as	O
one	O
of	O
the	O
most	O
original	O
games	O
of	O
2007	O
,	O
despite	O
criticisms	O
for	O
its	O
short	O
duration	O
and	O
limited	O
story	O
.	O
</s>
<s>
Portal	B-Application
is	O
often	O
cited	O
as	O
one	O
of	O
the	O
greatest	O
video	O
games	O
ever	O
made	O
.	O
</s>
<s>
Excluding	O
Steam	B-Application
download	O
sales	O
,	O
over	O
four	O
million	O
copies	O
of	O
the	O
game	O
have	O
been	O
sold	O
since	O
its	O
release	O
,	O
spawning	O
official	O
merchandise	O
from	O
Valve	O
including	O
plush	O
Companion	O
Cubes	O
,	O
as	O
well	O
as	O
fan	O
recreations	O
of	O
the	O
cake	O
and	O
portal	B-Application
gun	O
.	O
</s>
<s>
A	O
standalone	O
version	O
with	O
extra	O
puzzles	O
,	O
Portal	B-Application
:	O
Still	O
Alive	O
,	O
was	O
also	O
published	O
by	O
Valve	O
on	O
the	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
service	O
in	O
October	O
2008	O
exclusively	O
for	O
Xbox	B-Operating_System
360	I-Operating_System
.	O
</s>
<s>
A	O
sequel	O
,	O
Portal	B-Application
2	I-Application
,	O
was	O
released	O
in	O
2011	O
,	O
which	O
expanded	O
on	O
the	O
storyline	O
,	O
adding	O
several	O
gameplay	O
mechanics	O
and	O
a	O
cooperative	O
multiplayer	O
mode	O
.	O
</s>
<s>
In	O
Portal	B-Application
,	O
the	O
player	O
controls	O
the	O
protagonist	O
,	O
Chell	O
,	O
from	O
a	O
first-person	O
perspective	O
as	O
she	O
is	O
challenged	O
to	O
navigate	O
through	O
a	O
series	O
of	O
test	O
chambers	O
using	O
the	O
Aperture	O
Science	O
Handheld	O
Portal	B-Application
Device	O
,	O
or	O
portal	B-Application
gun	O
,	O
under	O
the	O
watchful	O
supervision	O
of	O
the	B-Application
artificial	I-Application
intelligence	I-Application
GLaDOS	O
.	O
</s>
<s>
The	O
portal	B-Application
gun	O
can	O
create	O
two	O
distinct	O
portal	B-Application
ends	O
,	O
orange	O
and	O
blue	O
.	O
</s>
<s>
The	O
portals	B-Application
create	O
a	O
visual	O
and	O
physical	O
connection	O
between	O
two	O
different	O
locations	O
in	O
three-dimensional	O
space	O
.	O
</s>
<s>
Neither	O
end	O
is	O
specifically	O
an	O
entrance	O
or	O
exit	O
;	O
all	O
objects	O
that	O
travel	O
through	O
one	O
portal	B-Application
will	O
exit	O
through	O
the	O
other	O
.	O
</s>
<s>
As	O
moving	O
objects	O
pass	O
through	O
portals	B-Application
,	O
they	O
come	O
through	O
the	O
exit	O
portal	B-Application
at	O
the	O
same	O
direction	O
that	O
the	O
exit	O
portal	B-Application
is	O
facing	O
and	O
with	O
the	O
same	O
speed	O
with	O
which	O
they	O
passed	O
through	O
the	O
entrance	O
portal	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
a	O
common	O
maneuver	O
is	O
to	O
place	O
a	O
portal	B-Application
some	O
distance	O
below	O
the	O
player	O
on	O
the	O
floor	O
,	O
jump	O
down	O
through	O
it	O
,	O
gaining	O
speed	O
in	O
freefall	O
,	O
and	O
emerge	O
through	O
the	O
other	O
portal	B-Application
on	O
a	O
wall	O
,	O
flying	O
over	O
a	O
gap	O
or	O
another	O
obstacle	O
.	O
</s>
<s>
If	O
portal	B-Application
ends	O
are	O
not	O
on	O
parallel	O
planes	O
,	O
the	O
character	O
passing	O
through	O
is	O
reoriented	O
to	O
be	O
upright	O
with	O
respect	O
to	O
gravity	O
after	O
leaving	O
a	O
portal	B-Application
end	O
.	O
</s>
<s>
Chell	O
and	O
all	O
other	O
objects	O
in	O
the	O
game	O
that	O
can	O
fit	O
into	O
the	O
portal	B-Application
ends	O
will	O
pass	O
through	O
the	O
portal	B-Application
.	O
</s>
<s>
However	O
,	O
a	O
portal	B-Application
shot	O
cannot	O
pass	O
through	O
an	O
open	O
portal	B-Application
;	O
it	O
will	O
simply	O
deactivate	O
or	O
create	O
a	O
new	O
portal	B-Application
in	O
an	O
offset	O
position	O
.	O
</s>
<s>
Creating	O
a	O
portal	B-Application
end	O
instantly	O
deactivates	O
an	O
existing	O
portal	B-Application
end	O
of	O
the	O
same	O
color	O
.	O
</s>
<s>
Moving	O
objects	O
,	O
glass	O
,	O
special	O
wall	O
surfaces	O
,	O
liquids	O
,	O
or	O
areas	O
that	O
are	O
too	O
small	O
will	O
not	O
be	O
able	O
to	O
anchor	O
portals	B-Application
.	O
</s>
<s>
Particle	O
fields	O
,	O
known	O
as	O
"	O
Emancipation	O
Grills	O
"	O
,	O
occasionally	O
called	O
"	O
Fizzlers	O
"	O
in	O
the	O
developer	O
commentary	O
,	O
exist	O
at	O
the	O
end	O
of	O
all	O
and	O
within	O
some	O
test	O
chambers	O
;	O
when	O
passed	O
through	O
,	O
they	O
will	O
deactivate	O
any	O
active	O
portals	B-Application
and	O
disintegrate	O
any	O
object	O
carried	O
through	O
.	O
</s>
<s>
These	O
fields	O
also	O
block	O
attempts	O
to	O
fire	O
portals	B-Application
through	O
them	O
.	O
</s>
<s>
In	O
Challenge	O
mode	O
,	O
levels	O
are	O
revisited	O
with	O
the	O
added	O
goal	O
of	O
completing	O
the	O
test	O
chamber	O
either	O
with	O
as	O
little	O
time	O
,	O
with	O
the	O
fewest	O
portals	B-Application
,	O
or	O
with	O
the	O
fewest	O
footsteps	O
possible	O
.	O
</s>
<s>
The	O
game	O
features	O
two	O
characters	O
:	O
the	O
player-controlled	O
silent	O
protagonist	O
named	O
Chell	O
,	O
and	O
GLaDOS	O
(	O
Genetic	O
Lifeform	O
and	O
Disk	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
)	O
,	O
a	O
computer	O
artificial	B-Application
intelligence	I-Application
that	O
monitors	O
and	O
directs	O
the	O
player	O
.	O
</s>
<s>
In	O
the	O
"	O
Lab	O
Rat	O
"	O
comic	O
created	O
by	O
Valve	O
to	O
bridge	O
the	O
gap	O
between	O
Portal	B-Application
and	O
Portal	B-Application
2	I-Application
,	O
Chell	O
's	O
records	O
reveal	O
she	O
was	O
ultimately	O
rejected	O
as	O
a	O
test	O
subject	O
for	O
having	O
"	O
too	O
much	O
tenacity	O
"	O
—	O
the	O
main	O
reason	O
Doug	O
Rattman	O
,	O
a	O
former	O
employee	O
of	O
Aperture	O
Science	O
,	O
moved	O
Chell	O
to	O
the	O
top	O
of	O
the	O
test	O
queue	O
.	O
</s>
<s>
Portal	B-Application
takes	O
place	O
in	O
the	O
Aperture	O
Science	O
Laboratories	O
Computer-Aided	O
Enrichment	O
Center	O
,	O
a	O
research	O
facility	O
responsible	O
for	O
the	O
creation	O
of	O
the	O
portal	B-Application
gun	O
.	O
</s>
<s>
The	O
first	O
two	O
tiers	O
,	O
the	O
Counter-Heimlich	O
Maneuver	O
(	O
a	O
maneuver	O
designed	O
to	O
ensure	O
choking	O
)	O
and	O
the	O
Take-A-Wish	B-Application
Foundation	I-Application
(	O
a	O
program	O
to	O
give	O
the	O
wishes	O
of	O
terminally	O
ill	O
children	O
to	O
adults	O
in	O
need	O
of	O
dreams	O
)	O
,	O
were	O
commercial	O
failures	O
and	O
led	O
to	O
an	O
investigation	O
of	O
the	O
company	O
by	O
the	O
U.S.	O
Senate	O
.	O
</s>
<s>
The	O
development	O
of	O
GLaDOS	O
,	O
an	O
artificially	B-Application
intelligent	I-Application
research	O
assistant	O
and	O
disk-operating	O
system	O
,	O
began	O
in	O
1986	O
in	O
response	O
to	O
Black	O
Mesa	O
's	O
work	O
on	O
similar	O
portal	B-Application
technology	O
.	O
</s>
<s>
Roughly	O
thirteen	O
years	O
later	O
,	O
work	O
on	O
GLaDOS	O
was	O
completed	O
and	O
the	O
untested	O
AI	B-Application
was	O
activated	O
during	O
the	O
company	O
's	O
bring-your-daughter-to-work	O
day	O
in	O
May	O
2000	O
.	O
</s>
<s>
Immediately	O
after	O
activation	O
,	O
the	O
facility	O
was	O
flooded	O
with	O
deadly	O
neurotoxin	O
by	O
the	O
AI	B-Application
.	O
</s>
<s>
Events	O
of	O
the	O
first	O
Half-Life	B-Application
game	O
occur	O
shortly	O
after	O
that	O
,	O
presumably	O
leaving	O
the	O
facility	O
forgotten	O
by	O
the	O
outside	O
world	O
due	O
to	O
apocalyptic	O
happenings	O
.	O
</s>
<s>
Wolpaw	O
,	O
in	O
describing	O
the	O
ending	O
of	O
Portal	B-Application
2	I-Application
,	O
affirmed	O
that	O
the	O
Combine	O
invasion	O
,	O
chronologically	O
taking	O
place	O
after	O
Half-Life	B-Application
and	O
before	O
Half-Life	B-Application
2	I-Application
,	O
had	O
occurred	O
before	O
Portal	B-Application
2s	I-Application
events	O
.	O
</s>
<s>
At	O
the	O
time	O
of	O
events	O
depicted	O
in	O
Portal	B-Application
,	O
the	O
facility	O
seems	O
to	O
be	O
long-deserted	O
,	O
although	O
most	O
of	O
its	O
equipment	O
remains	O
operational	O
without	O
human	O
control	O
.	O
</s>
<s>
The	O
game	O
begins	O
with	O
Chell	O
waking	O
up	O
from	O
a	O
stasis	O
bed	O
and	O
hearing	O
instructions	O
from	O
GLaDOS	O
,	O
an	O
artificial	B-Application
intelligence	I-Application
,	O
about	O
upcoming	O
tests	O
.	O
</s>
<s>
Chell	O
enters	O
into	O
sequential	O
distinct	O
chambers	O
that	O
introduce	O
her	O
to	O
varying	O
challenges	O
to	O
solve	O
using	O
her	O
portal	B-Application
gun	O
,	O
with	O
GLaDOS	O
as	O
her	O
only	O
interaction	O
.	O
</s>
<s>
The	O
test	O
chambers	O
become	O
increasingly	O
dangerous	O
as	O
Chell	O
proceeds	O
,	O
including	O
a	O
live-fire	O
course	O
designed	O
for	O
military	O
androids	B-Application
,	O
as	O
well	O
as	O
chambers	O
flooded	O
with	O
a	O
hazardous	O
liquid	O
.	O
</s>
<s>
In	O
one	O
chamber	O
,	O
GLaDOS	O
forces	O
Chell	O
to	O
"	O
euthanize	O
"	O
a	O
Weighted	O
Companion	O
Cube	O
in	O
an	O
incinerator	B-Application
,	O
after	O
Chell	O
uses	O
it	O
for	O
assistance	O
.	O
</s>
<s>
After	O
Chell	O
completes	O
the	O
final	O
test	O
chamber	O
,	O
GLaDOS	O
manoeuvres	O
Chell	O
into	O
an	O
incinerator	B-Application
in	O
an	O
attempt	O
to	O
kill	O
her	O
.	O
</s>
<s>
Chell	O
escapes	O
with	O
the	O
portal	B-Application
gun	O
and	O
makes	O
her	O
way	O
through	O
the	O
maintenance	O
areas	O
within	O
the	O
Enrichment	O
Center	O
.	O
</s>
<s>
Chell	O
travels	O
further	O
through	O
the	O
maintenance	O
areas	O
,	O
discovering	O
dilapidated	O
backstage	O
areas	O
covered	O
in	O
graffiti	O
that	O
includes	O
statements	O
such	O
as	O
"	O
the	B-Application
cake	I-Application
is	I-Application
a	I-Application
lie	I-Application
"	O
,	O
and	O
pastiches	O
of	O
quotes	O
from	O
famous	O
poets	O
such	O
as	O
Henry	O
Wadsworth	O
Longfellow	O
and	O
Emily	O
Brontë	O
.	O
</s>
<s>
A	O
sphere	O
soon	O
falls	O
from	O
GLaDOS	O
and	O
Chell	O
drops	O
it	O
in	O
an	O
incinerator	B-Application
.	O
</s>
<s>
Portal	B-Application
began	O
with	O
the	O
2005	O
freeware	O
game	O
Narbacular	B-Application
Drop	I-Application
,	O
developed	O
by	O
students	O
of	O
the	O
DigiPen	O
Institute	O
of	O
Technology	O
.	O
</s>
<s>
Newell	O
said	O
he	O
was	O
impressed	O
with	O
the	O
team	O
as	O
"	O
they	O
had	O
actually	O
carried	O
the	O
concept	O
through	O
"	O
,	O
already	O
having	O
included	O
the	O
interaction	O
between	O
portals	B-Application
and	O
physics	O
,	O
completing	O
most	O
of	O
the	O
work	O
that	O
Valve	O
would	O
have	O
had	O
to	O
commit	O
on	O
their	O
own	O
.	O
</s>
<s>
To	O
test	O
the	O
effectiveness	O
of	O
the	O
portal	B-Application
mechanic	O
,	O
the	O
team	O
made	O
a	O
prototype	O
in	O
an	O
in-house	O
2D	O
game	O
engine	O
that	O
is	O
used	O
in	O
DigiPen	O
.	O
</s>
<s>
Certain	O
elements	O
were	O
retained	O
from	O
Narbacular	B-Application
Drop	I-Application
,	O
such	O
as	O
the	O
system	O
of	O
identifying	O
the	O
two	O
unique	O
portal	B-Application
endpoints	O
with	O
the	O
colors	O
orange	O
and	O
blue	O
.	O
</s>
<s>
A	O
key	O
difference	O
is	O
that	O
Portals	B-Application
portal	B-Application
gun	O
cannot	O
create	O
a	O
portal	B-Application
through	O
an	O
existing	O
portal	B-Application
,	O
unlike	O
in	O
Narbacular	B-Application
Drop	I-Application
.	O
</s>
<s>
Portal	B-Application
took	O
approximately	O
two	O
years	O
and	O
four	O
months	O
to	O
complete	O
after	O
the	O
DigiPen	O
team	O
was	O
brought	O
into	O
Valve	O
,	O
and	O
no	O
more	O
than	O
ten	O
people	O
were	O
involved	O
with	O
its	O
development	O
.	O
</s>
<s>
Playtesters	B-General_Concept
found	O
the	O
game	O
fun	O
but	O
asked	O
about	O
what	O
these	O
test	O
chambers	O
were	O
leading	O
towards	O
.	O
</s>
<s>
This	O
prompted	O
the	O
team	O
to	O
come	O
up	O
with	O
a	O
narrative	O
for	O
Portal	B-Application
.	O
</s>
<s>
The	O
team	O
worked	O
with	O
Marc	O
Laidlaw	O
,	O
the	O
writer	O
of	O
the	O
Valve	O
's	O
Half-Life	B-Application
series	O
,	O
to	O
fit	O
Portal	B-Application
into	O
the	O
Half-Life	B-Application
universe	O
.	O
</s>
<s>
This	O
was	O
done	O
,	O
in	O
part	O
,	O
due	O
to	O
the	O
limited	O
art	O
capabilities	O
of	O
the	O
small	O
team	O
;	O
instead	O
of	O
creating	O
new	O
assets	O
for	O
Portal	B-Application
,	O
they	O
reused	O
the	O
Half-Life	B-Application
2	I-Application
art	O
assets	O
.	O
</s>
<s>
Valve	O
hired	O
Erik	O
Wolpaw	O
and	O
Chet	O
Faliszek	O
to	O
write	O
Portal	B-Application
.	O
</s>
<s>
The	O
concept	O
of	O
a	O
computer	B-Application
AI	I-Application
guiding	O
the	O
player	O
through	O
experimental	O
facilities	O
to	O
test	O
the	O
portal	B-Application
gun	O
was	O
arrived	O
at	O
early	O
in	O
the	O
writing	O
process	O
.	O
</s>
<s>
They	O
drafted	O
early	O
lines	O
for	O
the	O
yet-named	O
"	O
polite	O
"	O
AI	B-Application
with	O
humorous	O
situations	O
,	O
such	O
as	O
requesting	O
the	O
player	O
's	O
character	O
to	O
"	O
assume	O
the	O
party	O
escort	O
submission	O
position	O
"	O
,	O
and	O
found	O
this	O
style	O
of	O
approach	O
to	O
be	O
well-suited	O
to	O
the	O
game	O
they	O
wanted	O
to	O
create	O
,	O
leading	O
to	O
the	O
creation	O
of	O
the	O
GLaDOS	O
character	O
.	O
</s>
<s>
Wolpaw	O
described	O
the	O
idea	O
of	O
using	O
cake	O
as	O
the	O
reward	O
came	O
about	O
as	O
"	O
at	O
the	O
beginning	O
of	O
the	O
Portal	B-Application
development	O
process	O
,	O
we	O
sat	O
down	O
as	O
a	O
group	O
to	O
decide	O
what	O
philosopher	O
or	O
school	O
of	O
philosophy	O
our	O
game	O
would	O
be	O
based	O
on	O
.	O
</s>
<s>
They	O
also	O
dropped	O
the	O
introduction	O
of	O
the	O
Rat	O
Man	O
,	O
a	O
character	O
who	O
left	O
the	O
messages	O
in	O
the	O
maintenance	O
areas	O
,	O
to	O
avoid	O
creating	O
too	O
much	O
narrative	O
for	O
the	O
game	O
,	O
though	O
the	O
character	O
was	O
developed	O
further	O
in	O
a	O
tie-in	O
comic	O
"	O
Lab	O
Rat	O
"	O
,	O
that	O
ties	O
Portal	B-Application
and	O
Portal	B-Application
2s	I-Application
story	O
together	O
.	O
</s>
<s>
According	O
to	O
project	O
lead	O
Kim	O
Swift	O
,	O
the	O
final	O
battle	O
with	O
GLaDOS	O
went	O
through	O
many	O
iterations	O
,	O
including	O
having	O
the	O
player	O
chased	O
by	O
James	O
Bond	O
lasers	O
,	O
which	O
was	O
partially	O
applied	O
to	O
the	O
turrets	O
,	O
Portal	B-Application
Kombat	I-Application
where	O
the	O
player	O
would	O
have	O
needed	O
to	O
redirect	O
rockets	O
while	O
avoiding	O
turret	O
fire	O
,	O
and	O
a	O
chase	O
sequence	O
following	O
a	O
fleeing	O
GLaDOS	O
.	O
</s>
<s>
Eventually	O
,	O
they	O
found	O
that	O
playtesters	B-General_Concept
enjoyed	O
a	O
rather	O
simple	O
puzzle	O
with	O
a	O
countdown	O
timer	O
near	O
the	O
end	O
;	O
Swift	O
noted	O
,	O
"	O
Time	O
pressure	O
makes	O
people	O
think	O
something	O
is	O
a	O
lot	O
more	O
complicated	O
than	O
it	O
really	O
is	O
"	O
,	O
and	O
Wolpaw	O
admitted	O
,	O
"	O
It	O
was	O
really	O
cheap	O
to	O
make	O
[	O
the	O
neurotoxin	O
gas ]	O
"	O
in	O
order	O
to	O
simplify	O
the	O
dialogue	O
during	O
the	O
battle	O
.	O
</s>
<s>
The	O
portal	B-Application
gun	O
's	O
full	O
name	O
,	O
Aperture	O
Science	O
Handheld	O
Portal	B-Application
Device	O
,	O
can	O
be	O
abbreviated	O
as	O
ASHPD	B-Application
,	O
which	O
resembles	O
a	O
shortening	O
of	O
the	O
name	O
Adrian	O
Shephard	O
,	O
the	O
protagonist	O
of	O
Half-Life	B-Application
:	I-Application
Opposing	I-Application
Force	I-Application
.	O
</s>
<s>
The	O
closing	O
credits	O
song	O
,	O
"	O
Still	O
Alive	O
"	O
,	O
was	O
written	O
by	O
Jonathan	O
Coulton	O
and	O
sung	O
by	O
Ellen	O
McLain	O
(	O
a	O
classically-trained	O
operatic	O
soprano	B-Application
)	O
as	O
the	O
GLaDOS	O
character	O
.	O
</s>
<s>
Wolpaw	O
notes	O
that	O
Coulton	O
was	O
invited	O
to	O
Valve	O
a	O
year	O
before	O
the	O
release	O
of	O
Portal	B-Application
,	O
though	O
it	O
was	O
not	O
yet	O
clear	O
where	O
Coulton	O
would	O
contribute	O
.	O
</s>
<s>
The	O
use	O
of	O
the	O
song	O
over	O
the	O
closing	O
credits	O
was	O
based	O
on	O
a	O
similar	O
concept	O
from	O
the	O
game	O
God	B-Application
Hand	I-Application
,	O
one	O
of	O
Wolpaw	O
's	O
favorite	O
titles	O
.	O
</s>
<s>
The	O
song	O
was	O
released	O
as	O
a	O
free	O
downloadable	O
song	O
for	O
the	O
music	B-Application
video	I-Application
game	I-Application
Rock	B-Application
Band	I-Application
on	O
April	O
1	O
,	O
2008	O
.	O
</s>
<s>
The	O
soundtrack	O
for	O
Portal	B-Application
was	O
released	O
as	O
a	O
part	O
of	O
The	B-Application
Orange	I-Application
Box	I-Application
Original	O
Soundtrack	O
.	O
</s>
<s>
The	O
soundtrack	O
was	O
released	O
in	O
a	O
four-disc	O
retail	O
bundle	O
,	O
Portal	B-Application
2	I-Application
:	O
Songs	O
To	O
Test	O
By	O
(	O
Collector	O
's	O
Edition	O
)	O
,	O
on	O
October	O
30	O
,	O
2012	O
,	O
featuring	O
music	O
from	O
both	O
games	O
.	O
</s>
<s>
The	O
soundtrack	O
was	O
released	O
via	O
Steam	B-Application
Music	O
on	O
September	O
24	O
,	O
2014	O
.	O
</s>
<s>
Portal	B-Application
was	O
first	O
released	O
as	O
part	O
of	O
The	B-Application
Orange	I-Application
Box	I-Application
for	O
Windows	O
and	O
Xbox	B-Operating_System
360	I-Operating_System
on	O
October	O
10	O
,	O
2007	O
,	O
and	O
for	O
the	O
PlayStation	B-Operating_System
3	I-Operating_System
on	O
December	O
11	O
,	O
2007	O
.	O
</s>
<s>
The	O
Windows	O
version	O
of	O
the	O
game	O
is	O
also	O
available	O
for	O
download	O
separately	O
through	O
Valve	O
's	O
content	O
delivery	O
system	O
,	O
Steam	B-Application
,	O
and	O
was	O
released	O
as	O
a	O
standalone	O
retail	O
product	O
on	O
April	O
9	O
,	O
2008	O
.	O
</s>
<s>
In	O
addition	O
to	O
Portal	B-Application
,	O
the	O
Box	O
also	O
included	O
Half-Life	B-Application
2	I-Application
and	O
its	O
two	O
add-on	O
episodes	O
,	O
as	O
well	O
as	O
Team	B-Application
Fortress	I-Application
2	I-Application
.	O
</s>
<s>
Portals	B-Application
inclusion	O
within	O
the	O
Box	O
was	O
considered	O
an	O
experiment	O
by	O
Valve	O
;	O
having	O
no	O
idea	O
of	O
the	O
success	O
of	O
Portal	B-Application
,	O
the	O
Box	O
provided	O
it	O
a	O
"	O
safety	O
net	O
"	O
via	O
means	O
of	O
these	O
other	O
games	O
.	O
</s>
<s>
Portal	B-Application
was	O
kept	O
to	O
a	O
modest	O
length	O
in	O
case	O
the	O
game	O
did	O
not	O
go	O
over	O
well	O
with	O
players	O
.	O
</s>
<s>
In	O
January	O
2008	O
,	O
Valve	O
released	O
a	O
special	O
demo	O
version	O
titled	O
Portal	B-Application
:	O
The	O
First	O
Slice	O
,	O
free	O
for	O
any	O
Steam	B-Application
user	O
using	O
Nvidia	O
graphics	O
hardware	O
as	O
part	O
of	O
a	O
collaboration	O
between	O
the	O
two	O
companies	O
.	O
</s>
<s>
It	O
also	O
comes	O
packaged	O
with	O
Half-Life	B-Application
2	I-Application
:	I-Application
Deathmatch	I-Application
,	O
Peggle	O
Extreme	O
,	O
and	O
Half-Life	B-Application
2	I-Application
:	I-Application
Lost	I-Application
Coast	I-Application
.	O
</s>
<s>
Valve	O
has	O
since	O
made	O
the	O
demo	O
available	O
to	O
all	O
Steam	B-Application
users	O
.	O
</s>
<s>
Portal	B-Application
is	O
the	O
first	O
Valve-developed	O
game	O
to	O
be	O
added	O
to	O
the	O
OS	O
X-compatible	O
list	O
of	O
games	O
available	O
on	O
the	O
launch	O
of	O
the	O
Steam	B-Application
client	I-Application
for	O
Mac	O
on	O
May	O
12	O
,	O
2010	O
,	O
supporting	O
Steam	B-Application
Play	O
,	O
in	O
which	O
buying	O
the	O
game	O
on	O
Macintosh	O
or	O
Windows	O
computer	O
makes	O
it	O
playable	O
on	O
both	O
.	O
</s>
<s>
As	O
part	O
of	O
the	O
promotion	O
,	O
Portal	B-Application
was	O
offered	O
as	O
a	O
free	O
game	O
for	O
any	O
Steam	B-Application
user	O
during	O
the	O
two	O
weeks	O
following	O
the	O
Mac	O
client	O
's	O
launch	O
.	O
</s>
<s>
Within	O
the	O
first	O
week	O
of	O
this	O
offer	O
,	O
over	O
1.5	O
million	O
copies	O
of	O
the	O
game	O
were	O
downloaded	O
through	O
Steam	B-Application
.	O
</s>
<s>
Valve	O
wrote	O
that	O
they	O
felt	O
that	O
Portal	B-Application
"	O
makes	O
physics	O
,	O
math	O
,	O
logic	O
,	O
spatial	O
reasoning	O
,	O
probability	O
,	O
and	O
problem-solving	O
interesting	O
,	O
cool	O
,	O
and	O
fun	O
"	O
,	O
a	O
necessary	O
feature	O
to	O
draw	O
children	O
into	O
learning	O
.	O
</s>
<s>
Portal	B-Application
:	O
Still	O
Alive	O
was	O
announced	O
as	O
an	O
exclusive	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
game	O
at	O
the	O
2008	O
E3	O
convention	O
,	O
and	O
was	O
released	O
on	O
October	O
22	O
,	O
2008	O
.	O
</s>
<s>
The	O
additional	O
content	O
was	O
based	O
on	O
levels	O
from	O
the	O
map	O
pack	O
Portal	B-Application
:	O
The	O
Flash	O
Version	O
created	O
by	O
We	O
Create	O
Stuff	O
and	O
contains	O
no	O
additional	O
story-related	O
levels	O
.	O
</s>
<s>
According	O
to	O
Valve	O
spokesman	O
Doug	O
Lombardi	O
,	O
Microsoft	O
had	O
previously	O
rejected	O
Portal	B-Application
on	O
the	O
platform	O
due	O
to	O
its	O
large	O
size	O
.	O
</s>
<s>
Portal	B-Application
:	O
Still	O
Alive	O
was	O
well	O
received	O
by	O
reviewers	O
.	O
</s>
<s>
com	O
's	O
Andrew	O
Hayward	O
stated	O
that	O
,	O
with	O
the	O
easier	O
access	O
and	O
lower	O
cost	O
than	O
paying	O
for	O
The	B-Application
Orange	I-Application
Box	I-Application
,	O
Portal	B-Application
is	O
now	O
"	O
stronger	O
than	O
ever	O
"	O
.	O
</s>
<s>
IGN	O
editor	O
Cam	O
Shea	O
ranked	O
it	O
fifth	O
on	O
his	O
top	O
10	O
list	O
of	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
games	O
.	O
</s>
<s>
He	O
stated	O
that	O
it	O
was	O
debatable	O
whether	O
an	O
owner	O
of	O
The	B-Application
Orange	I-Application
Box	I-Application
should	O
purchase	O
this	O
,	O
as	O
its	O
added	O
levels	O
do	O
not	O
add	O
to	O
the	O
plot	O
.	O
</s>
<s>
The	O
game	O
ranked	O
7th	O
in	O
a	O
later	O
list	O
of	O
top	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
titles	O
compiled	O
by	O
IGN	O
's	O
staff	O
in	O
September	O
2010	O
.	O
</s>
<s>
During	O
2014	O
GPU	O
Technology	O
Conference	O
on	O
March	O
25	O
,	O
2014	O
,	O
Nvidia	O
announced	O
a	O
port	O
of	O
Portal	B-Application
to	O
the	O
Nvidia	B-Application
Shield	I-Application
,	O
their	O
Android	B-Application
handheld	O
;	O
the	O
port	O
was	O
released	O
on	O
May	O
12	O
,	O
2014	O
.	O
</s>
<s>
Alongside	O
Portal	B-Application
2	I-Application
,	O
Portal	B-Application
was	O
released	O
on	O
the	O
Nintendo	B-Application
Switch	I-Application
on	O
June	O
28	O
,	O
2022	O
as	O
part	O
of	O
Portal	B-Application
:	O
Companion	O
Collection	O
,	O
developed	O
by	O
Valve	O
and	O
Nvidia	O
Lightspeed	O
Studios	O
.	O
</s>
<s>
Nvidia	O
announced	O
Portal	B-Application
With	O
RTX	O
,	O
a	O
remaster	O
intended	O
to	O
show	O
off	O
the	O
functionality	O
of	O
the	O
company	O
's	O
GeForce	B-Device
40	I-Device
series	I-Device
cards	O
with	O
real-time	B-Algorithm
ray	I-Algorithm
tracing	I-Algorithm
,	O
for	O
release	O
as	O
a	O
free	O
DLC	O
,	O
initially	O
planned	O
for	O
November	O
2022	O
.	O
</s>
<s>
Portal	B-Application
received	O
critical	O
acclaim	O
,	O
often	O
earning	O
more	O
praise	O
than	O
either	O
Half-Life	B-Application
2	I-Application
:	O
Episode	O
Two	O
or	O
Team	B-Application
Fortress	I-Application
2	I-Application
,	O
two	O
titles	O
also	O
included	O
in	O
The	B-Application
Orange	I-Application
Box	I-Application
.	O
</s>
<s>
Eurogamer	O
cited	O
that	O
"	O
the	O
way	O
the	O
game	O
progresses	O
from	O
being	O
a	O
simple	O
set	O
of	O
perfunctory	O
tasks	O
to	O
a	O
full-on	O
part	O
of	O
the	O
Half-Life	B-Application
story	O
is	O
absolute	O
genius	O
"	O
,	O
while	O
GameSpy	O
noted	O
,	O
"	O
What	O
Portal	B-Application
lacks	O
in	O
length	O
,	O
it	O
more	O
than	O
makes	O
up	O
for	O
in	O
exhilaration.	O
"	O
</s>
<s>
Aggregate	O
reviews	O
for	O
the	O
standalone	O
PC	O
version	O
of	O
Portal	B-Application
gave	O
the	O
game	O
a	O
90/100	O
through	O
28reviews	O
on	O
Metacritic	O
.	O
</s>
<s>
In	O
2011	O
,	O
Valve	O
stated	O
that	O
Portal	B-Application
had	O
sold	O
more	O
than	O
four	O
million	O
copies	O
through	O
the	O
retail	O
versions	O
,	O
including	O
the	O
standalone	O
game	O
and	O
The	B-Application
Orange	I-Application
Box	I-Application
,	O
and	O
from	O
the	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
version	O
.	O
</s>
<s>
Fans	O
have	O
created	O
plush	O
and	O
papercraft	O
versions	O
of	O
the	O
cube	O
and	O
the	O
various	O
turrets	O
,	O
as	O
well	O
as	O
PC	O
case	B-Architecture
mods	I-Architecture
and	O
models	O
of	O
the	O
Portal	B-Application
cake	O
and	O
portal	B-Application
gun	O
.	O
</s>
<s>
Jeep	O
Barnett	O
,	O
a	O
programmer	O
for	O
Portal	B-Application
,	O
noted	O
that	O
players	O
have	O
told	O
Valve	O
that	O
they	O
had	O
found	O
it	O
more	O
emotional	O
to	O
incinerate	O
the	O
Weighted	O
Companion	O
Cube	O
than	O
to	O
harm	O
one	O
of	O
the	O
"	O
Little	O
Sisters	O
"	O
from	O
BioShock	B-Application
.	O
</s>
<s>
I	O
went	O
in	O
expecting	O
a	O
slew	O
of	O
interesting	O
portal-based	O
puzzles	O
and	O
that	O
's	O
exactly	O
what	O
I	O
got	O
,	O
but	O
what	O
I	O
was	O
n't	O
expecting	O
was	O
some	O
of	O
the	O
funniest	O
pitch	O
black	O
humor	O
I	O
've	O
ever	O
heard	O
in	O
a	O
game	O
"	O
.	O
</s>
<s>
Writing	O
for	O
GameSetWatch	O
in	O
2009	O
,	O
columnist	O
Daniel	O
Johnson	O
pointed	O
out	O
similarities	O
between	O
Portal	B-Application
and	O
Erving	O
Goffman	O
's	O
essay	O
on	O
dramaturgy	O
,	O
The	O
Presentation	O
of	O
Self	O
in	O
Everyday	O
Life	O
,	O
which	O
equates	O
one	O
's	O
persona	O
to	O
the	O
front	O
and	O
backstage	O
areas	O
of	O
a	O
theater	O
.	O
</s>
<s>
Portal	B-Application
has	O
also	O
been	O
cited	O
as	O
a	O
strong	O
example	O
of	O
instructional	O
scaffolding	O
that	O
can	O
be	O
adapted	O
for	O
more	O
academic	O
learning	O
situations	O
,	O
as	O
the	O
player	O
,	O
through	O
careful	O
design	O
of	O
levels	O
by	O
Valve	O
,	O
is	O
first	O
hand-held	O
in	O
solving	O
simple	O
puzzles	O
with	O
many	O
hints	O
at	O
the	O
correct	O
solution	O
,	O
but	O
this	O
support	O
is	O
slowly	O
removed	O
as	O
the	O
player	O
progresses	O
in	O
the	O
game	O
,	O
and	O
completely	O
removed	O
when	O
the	O
player	O
reaches	O
the	O
second	O
half	O
of	O
the	O
game	O
.	O
</s>
<s>
Rock	O
,	O
Paper	O
,	O
Shotgun	O
's	O
Hamish	O
Todd	O
considered	O
Portal	B-Application
as	O
an	O
exemplary	O
means	O
of	O
game	O
design	O
by	O
demonstrating	O
a	O
series	O
of	O
chambers	O
after	O
the	O
player	O
has	O
obtained	O
the	O
portal	B-Application
gun	O
that	O
gently	O
introduce	O
the	O
concept	O
of	O
flinging	O
without	O
any	O
explicit	O
instructions	O
.	O
</s>
<s>
Portal	B-Application
was	O
exhibited	O
at	O
the	O
Smithsonian	O
Art	O
Exhibition	O
in	O
America	O
from	O
February	O
14	O
through	O
September	O
30	O
,	O
2012	O
.	O
</s>
<s>
Portal	B-Application
won	O
the	O
"	O
Action	O
"	O
section	O
for	O
the	O
platform	O
"	O
Modern	O
Windows	O
"	O
.	O
</s>
<s>
Since	O
its	O
release	O
Portal	B-Application
is	O
still	O
considered	O
one	O
of	O
the	O
best	O
video	O
games	O
of	O
all	O
time	O
,	O
having	O
been	O
included	O
on	O
several	O
cumulative	O
"	O
Top	O
Games	O
of	O
All	O
Time	O
"	O
lists	O
through	O
2018	O
.	O
</s>
<s>
Portal	B-Application
won	O
several	O
awards	O
:	O
</s>
<s>
At	O
the	O
2008	O
Game	O
Developers	O
Choice	O
Awards	O
,	O
Portal	B-Application
won	O
Game	O
of	O
the	O
Year	O
award	O
,	O
along	O
with	O
the	O
Innovation	O
Award	O
and	O
Best	O
Game	O
Design	O
award	O
.	O
</s>
<s>
IGN	O
honored	O
Portal	B-Application
with	O
several	O
awards	O
,	O
for	O
Best	O
Puzzle	O
Game	O
for	O
PC	O
and	O
Xbox	B-Operating_System
360	I-Operating_System
,	O
Most	O
Innovative	O
Design	O
for	O
PC	O
,	O
and	O
Best	O
End	O
Credit	O
Song	O
(	O
for	O
"	O
Still	O
Alive	O
"	O
)	O
for	O
Xbox	B-Operating_System
360	I-Operating_System
,	O
along	O
with	O
overall	O
honors	O
for	O
Best	O
Puzzle	O
Game	O
and	O
Most	O
Innovative	O
Design	O
.	O
</s>
<s>
In	O
its	O
Best	O
of	O
2007	O
,	O
GameSpot	O
honored	O
The	B-Application
Orange	I-Application
Box	I-Application
with	O
4	O
awards	O
in	O
recognition	O
of	O
Portal	B-Application
,	O
giving	O
out	O
honors	O
for	O
Best	O
Puzzle	O
Game	O
,	O
Best	O
New	O
Character(s )	O
(	O
for	O
GLaDOS	O
)	O
,	O
Funniest	O
Game	O
,	O
and	O
Best	O
Original	O
Game	O
Mechanic	O
(	O
for	O
the	O
portal	B-Application
gun	O
)	O
.	O
</s>
<s>
Portal	B-Application
was	O
awarded	O
Game	O
of	O
the	O
Year	O
(	O
PC	O
)	O
,	O
Best	O
Narrative	O
(	O
PC	O
)	O
,	O
and	O
Best	O
Innovation	O
(	O
PC	O
and	O
console	O
)	O
honors	O
by	O
1UP.com	O
in	O
its	O
2007	O
editorial	O
awards	O
.	O
</s>
<s>
Portal	B-Application
was	O
awarded	O
the	O
Game	O
of	O
the	O
Year	O
award	O
in	O
2007	O
by	O
Joystiq	O
,	O
Good	O
Game	O
,	O
and	O
Shacknews	O
.	O
</s>
<s>
In	O
Official	O
Xbox	B-Operating_System
Magazine	O
2007	O
Game	O
of	O
the	O
Year	O
Awards	O
,	O
Portal	B-Application
won	O
Best	O
New	O
Character	O
(	O
for	O
GLaDOS	O
)	O
,	O
Best	O
Original	O
Song	O
(	O
for	O
"	O
Still	O
Alive	O
"	O
)	O
,	O
and	O
Innovation	O
of	O
the	O
Year	O
.	O
</s>
<s>
In	O
GameSpy	O
's	O
2007	O
Game	O
of	O
the	O
Year	O
awards	O
,	O
Portal	B-Application
was	O
recognized	O
as	O
Best	O
Puzzle	O
Game	O
,	O
Best	O
Character	O
(	O
for	O
GLaDOS	O
)	O
,	O
and	O
Best	O
Sidekick	O
(	O
for	O
the	O
Weighted	O
Companion	O
Cube	O
)	O
.	O
</s>
<s>
The	O
webcomic	O
Penny	O
Arcade	O
awarded	O
Portal	B-Application
Best	O
Soundtrack	O
,	O
Best	O
Writing	O
,	O
and	O
Best	O
New	O
Game	O
Mechanic	O
in	O
its	O
satirical	O
2007	O
We	O
're	O
Right	O
Awards	O
.	O
</s>
<s>
Eurogamer	O
gave	O
Portal	B-Application
first	O
place	O
in	O
its	O
Top	O
50	O
Games	O
of	O
2007	O
rankings	O
.	O
</s>
<s>
IGN	O
also	O
placed	O
GLaDOS	O
,	O
(	O
from	O
Portal	B-Application
)	O
as	O
the	O
Video	O
Game	O
Villain	O
on	O
its	O
Top-100	O
Villains	O
List	O
.	O
</s>
<s>
Wired	O
considered	O
Portal	B-Application
to	O
be	O
one	O
of	O
the	O
most	O
influential	O
games	B-Application
of	I-Application
the	I-Application
first	I-Application
decade	I-Application
of	I-Application
the	I-Application
21st	I-Application
century	I-Application
,	O
believing	O
it	O
to	O
be	O
the	O
prime	O
example	O
of	O
quality	O
over	O
quantity	O
for	O
video	O
games	O
.	O
</s>
<s>
The	O
popularity	O
of	O
the	O
game	O
and	O
its	O
characters	O
led	O
Valve	O
to	O
develop	O
merchandise	O
for	O
Portal	B-Application
made	O
available	O
through	O
its	O
online	O
Valve	O
physical	O
merchandise	O
store	O
.	O
</s>
<s>
Other	O
products	O
available	O
through	O
the	O
Valve	O
store	O
include	O
T-shirts	O
and	O
Aperture	O
Science	O
coffee	O
mugs	O
and	O
parking	O
stickers	O
,	O
and	O
merchandise	O
relating	O
to	O
the	O
phrase	O
"	O
the	B-Application
cake	I-Application
is	I-Application
a	I-Application
lie	I-Application
"	O
,	O
which	O
has	O
become	O
an	O
internet	O
meme	O
.	O
</s>
<s>
An	O
unofficial	O
port	O
is	O
being	O
developed	O
on	O
the	O
Nintendo	B-Operating_System
64	I-Operating_System
console	O
.	O
</s>
<s>
A	O
modding	O
community	O
has	O
developed	O
around	O
Portal	B-Application
,	O
with	O
users	O
creating	O
their	O
own	O
test	O
chambers	O
and	O
other	O
in-game	O
modifications	O
.	O
</s>
<s>
The	O
group	O
"	O
We	O
Create	O
Stuff	O
"	O
created	O
an	O
Adobe	B-Operating_System
Flash	I-Operating_System
version	O
of	O
Portal	B-Application
,	O
titled	O
Portal	B-Application
:	O
The	O
Flash	O
Version	O
,	O
just	O
before	O
release	O
of	O
The	B-Application
Orange	I-Application
Box	I-Application
.	O
</s>
<s>
Another	O
mod	O
,	O
Portal	B-Application
:	O
Prelude	O
,	O
is	O
an	O
unofficial	O
prequel	O
developed	O
by	O
an	O
independent	O
team	O
of	O
three	O
that	O
focuses	O
on	O
the	O
pre-GLaDOS	O
era	O
of	O
Aperture	O
Science	O
,	O
and	O
contains	O
nineteen	O
additional	O
"	O
crafty	O
and	O
challenging	O
"	O
test	O
chambers	O
.	O
</s>
<s>
An	O
ASCII	B-Protocol
version	O
of	O
Portal	B-Application
was	O
created	O
by	O
Joe	O
Larson	O
.	O
</s>
<s>
An	O
unofficial	O
port	O
of	O
Portal	B-Application
to	O
the	O
iPhone	B-Device
using	O
the	O
Unity	B-Application
game	I-Application
engine	I-Application
was	O
created	O
but	O
only	O
consisted	O
of	O
a	O
single	O
room	O
from	O
the	O
game	O
.	O
</s>
<s>
Mari0	B-Application
is	O
a	O
fan-made	O
four-player	O
coop	O
mashup	O
of	O
the	O
original	O
Super	B-Application
Mario	I-Application
Bros	I-Application
.	I-Application
and	O
Portal	B-Application
.	O
</s>
<s>
Swift	O
stated	O
that	O
future	O
Portal	B-Application
developments	O
would	O
depend	O
on	O
the	O
community	O
's	O
reactions	O
,	O
saying	O
,	O
"	O
We	O
're	O
still	O
playing	O
it	O
by	O
ear	O
at	O
this	O
point	O
,	O
figuring	O
out	O
if	O
we	O
want	O
to	O
do	O
multiplayer	O
next	O
,	O
or	O
Portal	B-Application
2	I-Application
,	O
or	O
release	O
map	O
packs.	O
"	O
</s>
<s>
On	O
March	O
10	O
,	O
2010	O
,	O
Portal	B-Application
2	I-Application
was	O
officially	O
announced	O
for	O
a	O
release	O
late	O
in	O
that	O
year	O
;	O
the	O
announcement	O
was	O
preceded	O
by	O
an	O
alternate	O
reality	O
game	O
based	O
on	O
unexpected	O
patches	O
made	O
to	O
Portal	B-Application
that	O
contained	O
cryptic	O
messages	O
in	O
relation	O
to	O
Portal	B-Application
2s	I-Application
announcement	O
,	O
including	O
an	O
update	O
to	O
the	O
game	O
,	O
creating	O
a	O
different	O
ending	O
for	O
the	O
fate	O
of	O
Chell	O
.	O
</s>
<s>
Though	O
Portal	B-Application
2	I-Application
was	O
originally	O
announced	O
for	O
a	O
Q4	O
2010	O
release	O
,	O
the	O
game	O
was	O
released	O
on	O
April	O
19	O
,	O
2011	O
.	O
</s>
