<s>
Fortified	B-Application
Zone	I-Application
,	O
known	O
in	O
Japan	O
as	O
is	O
a	O
1991	B-Application
video	O
game	O
developed	O
and	O
published	O
by	O
Jaleco	O
for	O
the	O
Game	B-Device
Boy	I-Device
.	O
</s>
<s>
It	O
was	O
first	O
released	O
in	O
Japan	O
on	O
February	O
26	O
,	O
1991	B-Application
and	O
later	O
released	O
in	O
North	O
America	O
in	O
September	O
1991	B-Application
.	O
</s>
<s>
It	O
was	O
later	O
added	O
to	O
the	O
Nintendo	B-Operating_System
3DS	I-Operating_System
's	O
Virtual	B-Application
Console	I-Application
on	O
July	O
7	O
,	O
2011	O
,	O
but	O
the	O
Australia	O
region	O
had	O
it	O
added	O
on	O
July	O
28	O
,	O
2011	O
.	O
</s>
<s>
Fortified	B-Application
Zone	I-Application
's	O
plot	O
follows	O
two	O
Mercenaries	O
named	O
Masato	O
Kanzaki	O
and	O
Mizuki	O
Makimura	O
as	O
they	O
infiltrate	O
a	O
literal	O
fortified	B-Application
zone	I-Application
,	O
where	O
they	O
must	O
take	O
on	O
mercenaries	O
,	O
soldiers	O
,	O
robots	O
and	O
monsters	O
before	O
destroying	O
the	O
central	O
complex	O
at	O
the	O
fortified	B-Application
zone	I-Application
's	O
heart	O
.	O
</s>
<s>
Fortified	B-Application
Zone	I-Application
allows	O
the	O
player	O
to	O
switch	O
between	O
two	O
characters	O
during	O
game	O
play	O
.	O
</s>
<s>
The	O
game	O
was	O
the	O
first	O
entry	O
in	O
the	O
Ikari	O
no	O
Yōsai	O
series	O
,	O
and	O
was	O
followed	O
by	O
two	O
sequels	O
:	O
Ikari	O
no	O
Yōsai	O
2	O
for	O
the	O
Game	B-Device
Boy	I-Device
(	O
which	O
was	O
released	O
only	O
in	O
Japan	O
)	O
,	O
and	O
Ikari	O
no	O
Yōsai	O
for	O
the	O
Super	O
Famicom	O
(	O
released	O
outside	O
Japan	O
as	O
Operation	B-Application
Logic	I-Application
Bomb	I-Application
for	O
the	O
Super	O
NES	O
)	O
.	O
</s>
<s>
The	O
former	O
was	O
later	O
re-released	O
for	O
the	O
Japanese	O
3DS	B-Operating_System
Virtual	B-Application
Console	I-Application
on	O
January	O
11	O
,	O
2012	O
.	O
</s>
<s>
Survival	O
of	O
the	O
Fastest	O
,	O
the	O
debut	O
album	O
of	O
Irish	O
thrash	O
metal	O
band	O
Gama	O
Bomb	O
features	O
the	O
song	O
'	O
Fortified	B-Application
Zone	I-Application
 '	O
based	O
on	O
the	O
game	O
.	O
</s>
