<s>
Grappling	B-Application
Hook	I-Application
is	O
a	O
first-person	O
shooter	O
video	O
game	O
which	O
contains	O
both	O
platform	O
and	O
puzzle	O
elements	O
.	O
</s>
<s>
It	O
was	O
released	O
on	O
September	O
18	O
,	O
2009	O
for	O
the	O
Windows	O
platform	O
and	O
on	O
September	O
21	O
for	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
a	O
Linux	B-Application
version	O
was	O
later	O
released	O
.	O
</s>
<s>
The	O
player	O
must	O
collect	O
passcodes	O
from	O
throughout	O
31	O
three	O
dimensional	O
stages	O
,	O
using	O
the	O
titular	O
grappling	B-Application
hook	I-Application
to	O
swing	O
from	O
green	O
surfaces	O
in	O
order	O
to	O
progress	O
.	O
</s>
<s>
The	O
game	O
was	O
created	O
by	O
German	O
developer	O
Christian	O
Teister	O
,	O
the	O
sole	O
member	O
of	O
SpeedRunGames	O
,	O
who	O
had	O
previously	O
worked	O
on	O
some	O
smaller	O
indie	O
games	O
and	O
the	O
stealth	O
game	O
Velvet	B-Application
Assassin	I-Application
.	O
</s>
<s>
Inspired	O
by	O
a	O
fast-paced	O
first-person	O
shooter	O
mod	O
called	O
Cold	O
Ice	O
,	O
Teister	O
wished	O
to	O
couple	O
the	O
mod	O
's	O
speed	O
with	O
the	O
puzzle	O
gameplay	O
made	O
possible	O
by	O
the	O
grappling	B-Application
hook	I-Application
.	O
</s>
<s>
Grappling	B-Application
Hook	I-Application
has	O
little	O
plot	O
.	O
</s>
<s>
In	O
later	O
stages	O
,	O
defensive	O
turrets	O
begin	O
to	O
appear	O
,	O
firing	O
directly	O
at	O
the	O
player-character	O
,	O
and	O
swinging	O
with	O
the	O
grappling	B-Application
hook	I-Application
also	O
becomes	O
more	O
difficult	O
,	O
requiring	O
the	O
player	O
to	O
time	O
the	O
release	O
of	O
the	O
grappling	B-Application
hook	I-Application
very	O
precisely	O
.	O
</s>
<s>
In	O
addition	O
,	O
grappling	B-Application
hook	I-Application
jumps	O
may	O
require	O
leaps	O
of	O
faith	O
-	O
the	O
next	O
green	O
surface	O
to	O
grapple	O
from	O
may	O
not	O
be	O
visible	O
until	O
after	O
the	O
player-character	O
has	O
been	O
launched	O
through	O
the	O
air	O
.	O
</s>
<s>
Within	O
this	O
mode	O
the	O
player	O
can	O
create	O
Grappling	B-Application
Hook	I-Application
stages	O
,	O
each	O
of	O
which	O
takes	O
the	O
form	O
of	O
an	O
octree	B-Data_Structure
,	O
a	O
cube	O
which	O
has	O
been	O
divided	O
into	O
eight	O
equal	O
parts	O
and	O
then	O
divided	O
further	O
.	O
</s>
<s>
SpeedRunGames	O
is	O
a	O
one-man	O
development	O
outfit	O
run	O
by	O
computational	B-General_Concept
visualistics	I-General_Concept
student	O
Christian	O
Teister	O
.	O
</s>
<s>
Having	O
studied	O
since	O
2001	O
,	O
Teister	O
developed	O
some	O
small	O
video	O
games	O
before	O
being	O
hired	O
to	O
work	O
on	O
the	O
stealth	O
video	O
game	O
Velvet	B-Application
Assassin	I-Application
during	O
2008	O
and	O
early	O
2009	O
.	O
</s>
<s>
Work	O
on	O
Grappling	B-Application
Hook	I-Application
began	O
after	O
the	O
developer	O
finished	O
work	O
on	O
Velvet	B-Application
Assassin	I-Application
,	O
development	O
of	O
Grappling	B-Application
Hook	I-Application
began	O
in	O
March	O
2009	O
.	O
</s>
<s>
The	O
previously	O
created	O
smaller	O
games	O
gave	O
Teister	O
the	O
experience	O
necessary	O
to	O
undertake	O
Grappling	B-Application
Hook	I-Application
.	O
</s>
<s>
One	O
,	O
a	O
mobile	B-Application
game	I-Application
named	O
Gladiator	O
,	O
provided	O
the	O
animation	O
system	O
used	O
in	O
Grappling	B-Application
Hook	I-Application
.	O
</s>
<s>
Grappling	B-Application
Hook	I-Application
was	O
inspired	O
by	O
a	O
Half-Life	B-Application
mod	O
called	O
Cold	O
Ice	O
.	O
</s>
<s>
Teister	O
wanted	O
to	O
build	O
on	O
the	O
"	O
feeling	O
of	O
acceleration	O
and	O
velocity	O
"	O
from	O
Cold	O
Ice	O
with	O
the	O
use	O
of	O
the	O
grappling	B-Application
hook	I-Application
;	O
"	O
I	O
think	O
the	O
spatial	O
puzzles	O
are	O
perfect	O
to	O
encourage	O
the	O
player	O
to	O
explore	O
how	O
the	O
grappling	B-Application
hook	I-Application
can	O
be	O
used.	O
"	O
</s>
