<s>
Sunless	B-Application
Sea	I-Application
is	O
a	O
survival/exploration	O
role-playing	O
video	O
game	O
with	O
roguelike	O
elements	O
developed	O
by	O
Failbetter	O
Games	O
.	O
</s>
<s>
The	O
game	O
was	O
released	O
on	O
6	O
February	O
2015	O
for	O
Windows	B-Application
and	O
OS	B-Operating_System
X	I-Operating_System
following	O
a	O
successful	O
Kickstarter	O
campaign	O
to	O
crowdfund	O
the	O
project	O
.	O
</s>
<s>
The	O
game	O
takes	O
place	O
in	O
the	O
universe	O
of	O
Failbetter	O
's	O
browser	B-Protocol
adventure	O
game	O
Fallen	B-Application
London	I-Application
,	O
in	O
which	O
Victorian-era	O
London	O
has	O
been	O
moved	O
beneath	O
the	O
earth	O
's	O
surface	O
to	O
the	O
edge	O
of	O
the	O
Unterzee	O
,	O
a	O
vast	O
underground	O
ocean	O
.	O
</s>
<s>
On	O
11	O
October	O
2016	O
,	O
the	O
game	O
's	O
first	O
downloadable	B-Protocol
content	I-Protocol
Zubmariner	B-Application
was	O
released	O
,	O
which	O
allows	O
players	O
to	O
explore	O
beneath	O
the	O
surface	O
of	O
the	O
"	O
zee	O
"	O
.	O
</s>
<s>
A	O
sequel	O
,	O
Sunless	B-Application
Skies	I-Application
,	O
was	O
announced	O
in	O
September	O
2016	O
.	O
</s>
<s>
The	O
player	O
can	O
win	O
by	O
achieving	O
their	O
chosen	O
ambition	O
,	O
such	O
as	O
becoming	O
Fallen	B-Application
London	I-Application
's	O
most	O
celebrated	O
explorer	O
or	O
amassing	O
enough	O
wealth	O
to	O
retire	O
.	O
</s>
<s>
Several	O
bits	O
of	O
writing	O
and	O
settings	O
in	O
the	O
game	O
are	O
literary	O
allusions	O
–	O
for	O
instance	O
,	O
the	O
very	O
premise	O
of	O
a	O
subterranean	O
"	O
Sunless	B-Application
Sea	I-Application
"	O
is	O
a	O
reference	O
to	O
the	O
poem	O
"	O
Kubla	O
Khan	O
"	O
by	O
Samuel	O
Taylor	O
Coleridge	O
,	O
which	O
is	O
further	O
reflected	O
by	O
the	O
existence	O
of	O
a	O
Khanate	O
and	O
an	O
"	O
Abora	O
Gate	O
"	O
.	O
</s>
<s>
On	O
3	O
September	O
2013	O
,	O
Failbetter	O
Games	O
launched	O
a	O
Kickstarter	O
campaign	O
to	O
crowdfund	O
Sunless	B-Application
Sea	I-Application
with	O
a	O
funding	O
goal	O
of	O
£	O
60,000	O
.	O
</s>
<s>
On	O
13	O
May	O
2014	O
,	O
the	O
studio	O
launched	O
a	O
Greenlight	O
campaign	O
to	O
release	O
the	O
game	O
on	O
Steam	B-Application
.	O
</s>
<s>
On	O
17	O
June	O
,	O
the	O
game	O
was	O
soft	O
launched	O
on	O
the	O
developer	O
's	O
website	O
,	O
a	O
Steam	B-Application
early	O
access	O
build	O
was	O
later	O
released	O
on	O
1	O
July	O
.	O
</s>
<s>
A	O
PlayStation	B-Operating_System
4	I-Operating_System
version	O
,	O
that	O
includes	O
the	O
Zubmariner	B-Application
expansion	O
,	O
was	O
released	O
in	O
August	O
2018	O
and	O
a	O
Nintendo	B-Application
Switch	I-Application
version	O
,	O
also	O
including	O
the	O
Zubmariner	B-Application
expansion	O
,	O
was	O
released	O
on	O
23	O
April	O
2020	O
.	O
</s>
<s>
The	B-Device
Xbox	I-Device
One	I-Device
version	O
was	O
released	O
the	O
next	O
day	O
,	O
on	O
the	O
24th	O
of	O
April	O
2020	O
.	O
</s>
<s>
Sunless	B-Application
Sea	I-Application
received	O
mostly	O
positive	O
reviews	O
from	O
professional	O
critics	O
on	O
launch	O
,	O
with	O
the	O
writing	O
and	O
setting	O
being	O
the	O
most	O
highly	O
praised	O
aspects	O
of	O
the	O
game	O
.	O
</s>
<s>
IGN	O
awarded	O
it	O
8.3	O
out	O
of	O
10	O
saying	O
"	O
Sunless	B-Application
Sea	I-Application
gives	O
you	O
a	O
wonderful	O
world	O
to	O
explore	O
that	O
's	O
packed	O
with	O
memorable	O
written	O
vignettes	O
and	O
danger.	O
"	O
</s>
