<s>
Knytt	B-Application
Underground	I-Application
is	O
a	O
2D	O
adventure	O
game	O
in	O
the	O
exploration	O
subgenre	O
similar	O
to	O
Metroidvania	O
games	O
,	O
with	O
elements	O
of	O
arcade	O
platformers	O
,	O
combining	O
the	O
mechanics	O
of	O
the	O
developer	O
's	O
previous	O
games	O
,	O
Knytt	O
and	O
Within	O
a	O
Deep	O
Forest	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
Swedish	O
programmer	O
Nicklas	O
Nygren	O
and	O
released	O
in	O
late	O
2012	O
,	O
with	O
the	O
PlayStation	B-Device
platforms	O
PS3	B-Operating_System
and	O
Vita	B-Device
seeing	O
the	O
first	O
launch	O
.	O
</s>
<s>
Knytt	B-Application
Underground	I-Application
is	O
a	O
side-scrolling	O
open	O
action-adventure	O
,	O
with	O
the	O
exploration	O
of	O
a	O
metroidvania	O
.	O
</s>
<s>
From	O
Within	O
a	O
Deep	O
Forest	O
it	O
incorporates	O
the	O
ability	O
to	O
transform	O
into	O
a	O
bouncing	B-Application
ball	I-Application
.	O
</s>
<s>
In	O
July	O
2012	O
,	O
Nifflas	O
announced	O
that	O
he	O
was	O
working	O
on	O
Knytt	B-Application
Underground	I-Application
,	O
and	O
that	O
it	O
is	O
his	O
biggest	O
game	O
yet	O
.	O
</s>
<s>
It	O
was	O
released	O
on	O
the	O
PlayStation	B-Device
Network	O
for	O
PlayStation	B-Operating_System
3	I-Operating_System
and	O
PS	B-Device
Vita	I-Device
in	O
late	O
December	O
2012	O
,	O
and	O
the	O
console	O
versions	O
include	O
extra	O
content	O
.	O
</s>
<s>
A	O
Wii	B-Device
U	I-Device
version	O
of	O
the	O
game	O
was	O
confirmed	O
in	O
August	O
2013	O
,	O
and	O
was	O
being	O
ported	O
by	O
Nygren	O
's	O
colleague	O
Mathias	O
Kærlev	O
.	O
</s>
<s>
Besides	O
Nifflas	O
 '	O
own	O
songs	O
,	O
Knytt	B-Application
Underground	I-Application
includes	O
music	O
by	O
D	O
Fast	O
,	O
David	O
Kanaga	O
,	O
Fredrik	O
Häthén	O
,	O
LPChip	O
,	O
Jonas	O
Mattebo	O
,	O
Stephen	O
Ascher	O
,	O
Void	O
Pointer	O
,	O
and	O
Yann	O
Van	O
Der	O
Cruyssen	O
.	O
</s>
