<s>
Attack	B-Operating_System
of	I-Operating_System
the	I-Operating_System
Mutant	I-Operating_System
Artificial	I-Operating_System
Trees	I-Operating_System
is	O
a	O
free	O
online	O
video	O
game	O
developed	O
as	O
part	O
of	O
a	O
marketing	O
campaign	O
by	O
the	O
National	O
Christmas	O
Tree	O
Association	O
in	O
2004	O
.	O
</s>
<s>
Players	O
are	O
called	O
upon	O
to	O
pelt	O
mutant	O
artificial	O
Christmas	O
trees	O
with	O
snowballs	B-Language
,	O
while	O
avoiding	O
the	O
elves	O
interspersed	O
between	O
the	O
garishly	O
colored	O
mutant	O
trees	O
.	O
</s>
<s>
Salon	O
writer	O
Andrew	O
Leonard	O
said	O
of	O
Attack	B-Operating_System
of	I-Operating_System
the	I-Operating_System
Mutant	I-Operating_System
Artificial	I-Operating_System
Christmas	I-Operating_System
Trees	I-Operating_System
,	O
"	O
(	O
the	O
game	O
is	O
)	O
diverting	O
for	O
about	O
three	O
nanoseconds	O
less	O
,	O
if	O
you	O
give	O
in	O
to	O
the	O
urge	O
to	O
pelt	O
the	O
annoying	O
elf	O
,	O
for	O
which	O
you	O
are	O
unfairly	O
punished	O
"	O
.	O
</s>
