<s>
Sentinel	B-Application
is	O
a	O
1990	O
video	O
game	O
developed	O
by	O
Imagineering	O
and	O
published	O
by	O
Atari	O
for	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
.	O
</s>
<s>
It	O
is	O
the	O
only	O
light	O
gun	O
game	O
ever	O
released	O
for	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
platform	O
.	O
</s>
<s>
It	O
was	O
re-released	O
with	O
improved	O
graphics	O
for	O
the	O
Atari	B-General_Concept
7800	I-General_Concept
in	O
1991	O
.	O
</s>
<s>
It	O
uses	O
the	O
XE	B-Device
light	I-Device
gun	I-Device
,	O
an	O
accessory	O
for	O
the	O
2600	O
and	O
7800	O
platforms	O
.	O
</s>
<s>
The	O
game	O
is	O
one	O
of	O
two	O
light	O
gun	O
games	O
for	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
,	O
however	O
the	O
other	O
,	O
called	O
simply	O
Shooting	O
Arcade	O
,	O
was	O
never	O
released	O
.	O
</s>
<s>
A	O
version	O
of	O
the	O
game	O
for	O
the	O
Atari	B-General_Concept
7800	I-General_Concept
platform	O
with	O
improved	O
graphics	O
was	O
developed	O
and	O
released	O
in	O
Europe	O
only	O
in	O
1991	O
.	O
</s>
<s>
As	O
such	O
,	O
Sentinel	B-Application
is	O
the	O
final	O
official	O
European	O
release	O
for	O
the	O
Atari	B-General_Concept
7800	I-General_Concept
platform	O
.	O
</s>
<s>
The	O
player	O
takes	O
control	O
of	O
a	O
scientist	O
piloting	O
a	O
glowing	O
orb	O
they	O
invented	O
named	O
the	O
Sentinel	B-Application
,	O
which	O
can	O
absorb	O
and	O
store	O
energy	O
.	O
</s>
<s>
When	O
aliens	O
invade	O
Earth	O
,	O
the	O
scientist	O
journeys	O
in	O
the	O
Sentinel	B-Application
to	O
four	O
alien	O
planets	O
–	O
Alptaurus	O
,	O
Ceruptus	O
,	O
Vulnavium	O
,	O
and	O
Asceptron	O
–	O
to	O
destroy	O
their	O
power	O
stations	O
,	O
each	O
guarded	O
by	O
an	O
alien	O
lord	O
.	O
</s>
<s>
The	O
game	O
is	O
similar	O
to	O
the	O
arcade	O
game	O
Crossbow	B-Application
in	O
that	O
the	O
player	O
uses	O
the	O
light	O
gun	O
to	O
shoot	O
enemy	O
targets	O
in	O
order	O
to	O
protect	O
the	O
Sentinel	B-Application
orb	O
hovering	O
above	O
the	O
surface	O
of	O
a	O
planet	O
.	O
</s>
<s>
A	O
May	O
2004	O
review	O
of	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
version	O
by	O
the	O
Video	O
Games	O
Critic	O
website	O
was	O
overwhelmingly	O
negative	O
with	O
a	O
score	O
of	O
"	O
F	O
"	O
.	O
</s>
<s>
He	O
compared	O
it	O
to	O
Crossbow	B-Application
,	O
but	O
called	O
Sentinel	B-Application
"	O
not	O
as	O
good	O
or	O
as	O
well	O
known	O
as	O
that	O
arcade	O
classic	O
"	O
.	O
</s>
