<s>
Sky	B-Operating_System
Shadow	I-Operating_System
is	O
a	O
clone	O
of	O
the	O
1981	O
Defender	B-Application
arcade	O
video	O
game	O
published	O
by	O
MacSoft	O
for	O
the	O
Macintosh	B-Device
in	O
1990	O
.	O
</s>
<s>
It	O
was	O
programmed	O
by	O
Patrick	O
Buckland	O
who	O
also	O
wrote	O
Crystal	B-Device
Quest	I-Device
.	O
</s>
<s>
Sky	B-Operating_System
Shadow	I-Operating_System
was	O
critically	O
acclaimed	O
when	O
originally	O
released	O
,	O
featuring	O
detailed	O
graphics	O
and	O
fast-paced	O
gameplay	O
.	O
</s>
<s>
Macworld	O
praised	O
Sky	B-Operating_System
Shadow	I-Operating_System
's	O
graphics	O
and	O
sound	O
effects	O
as	O
well	O
as	O
its	O
gameplay	O
,	O
stating	O
that	O
"	O
Sky	B-Operating_System
Shadow	I-Operating_System
is	O
an	O
engaging	O
,	O
fun	O
,	O
and	O
highly	O
addictive	O
game	O
"	O
.	O
</s>
