<s>
A	O
hidden	B-Application
object	I-Application
game	I-Application
,	O
also	O
called	O
hidden	O
picture	O
or	O
hidden	O
object	O
puzzle	O
adventure	O
(	O
HOPA	O
)	O
,	O
is	O
a	O
puzzle	O
video	O
game	O
genre	O
in	O
which	O
the	O
player	O
must	O
find	O
items	O
from	O
a	O
list	O
that	O
are	O
hidden	O
within	O
a	O
scene	O
.	O
</s>
<s>
Hidden	B-Application
object	I-Application
games	I-Application
are	O
a	O
popular	O
trend	O
in	O
casual	O
gaming	O
.	O
</s>
<s>
Time-limited	O
trial	O
versions	O
of	O
these	O
games	O
are	O
usually	O
available	O
for	O
download	O
,	O
although	O
many	O
are	O
free	O
to	O
download	O
on	O
app	B-Application
stores	I-Application
.	O
</s>
<s>
In	O
a	O
hidden	B-Application
object	I-Application
game	I-Application
,	O
the	O
player	O
wanders	O
from	O
one	O
place	O
to	O
another	O
to	O
discover	O
objects	O
that	O
allow	O
the	O
player	O
to	O
finish	O
the	O
game	O
.	O
</s>
<s>
Hidden	B-Application
object	I-Application
games	I-Application
originated	O
in	O
print	O
publications	O
such	O
as	O
the	O
I	O
Spy	O
books	O
or	O
a	O
regular	O
feature	O
in	O
Highlights	O
for	O
Children	O
,	O
in	O
which	O
the	O
reader	O
was	O
given	O
a	O
list	O
of	O
objects	O
to	O
find	O
hidden	O
in	O
a	O
cluttered	O
illustration	O
or	O
photograph	O
.	O
</s>
<s>
An	O
early	O
hidden	B-Application
object	I-Application
game	I-Application
was	O
Mother	O
Goose	O
:	O
Hidden	O
Pictures	O
,	O
released	O
for	O
the	O
CD-i	B-Device
in	O
1991	O
.	O
</s>
<s>
Mystery	B-Application
Case	I-Application
Files	I-Application
:	I-Application
Huntsville	I-Application
,	O
released	O
by	O
Big	O
Fish	O
Games	O
in	O
2005	O
,	O
came	O
at	O
the	O
rise	O
of	O
casual	O
gaming	O
in	O
the	O
mid-2000s	O
.	O
</s>
<s>
Mystery	B-Application
Case	I-Application
Files	I-Application
:	I-Application
Huntsville	I-Application
established	O
many	O
of	O
the	O
principles	O
in	O
both	O
game	O
play	O
and	O
narrative	O
that	O
would	O
be	O
predominate	O
in	O
hidden	B-Application
object	I-Application
games	I-Application
since	O
.	O
</s>
<s>
For	O
example	O
,	O
Hidden	B-Application
Folks	I-Application
is	O
considered	O
more	O
of	O
a	O
searching	O
game	O
,	O
as	O
to	O
find	O
one	O
character	O
among	O
hundreds	O
on	O
the	O
screen	O
that	O
look	O
similar	O
to	O
each	O
other	O
,	O
similar	O
to	O
Where	O
's	O
Wally	O
.	O
</s>
<s>
Huntsville	B-Application
broke	O
prior	O
sales	O
of	O
casual	O
games	O
,	O
and	O
the	O
series	O
 '	O
third	O
iteration	O
Mystery	B-Application
Case	I-Application
Files	I-Application
:	I-Application
Ravenhearst	I-Application
was	O
the	O
third	O
best-selling	O
game	O
on	O
personal	B-Device
computers	I-Device
during	O
the	O
end-of-year	O
sales	O
period	O
of	O
2007	O
.	O
</s>
<s>
Hidden	B-Application
object	I-Application
games	I-Application
draw	O
players	O
who	O
were	O
fans	O
of	O
games	O
like	O
Myst	B-Application
,	O
and	O
player	O
demographics	O
skew	O
toward	O
women	O
who	O
are	O
over	O
55	O
years	O
of	O
age	O
.	O
</s>
