<s>
XOR	B-Application
is	O
a	O
puzzle	O
video	O
game	O
created	O
by	O
Astral	O
Software	O
and	O
published	O
by	O
Logotron	O
in	O
1987	O
for	O
the	O
Acorn	B-Device
Electron	I-Device
,	O
Amiga	B-Device
,	O
Amstrad	B-Device
CPC	I-Device
,	O
Atari	B-Device
ST	I-Device
,	O
BBC	B-Device
Micro	I-Device
,	O
Commodore	O
64	O
,	O
and	O
ZX	B-Operating_System
Spectrum	I-Operating_System
.	O
</s>
<s>
The	O
player	O
controls	O
two	O
shields	O
,	O
Magus	O
and	O
Questor	O
,	O
which	O
can	O
be	O
moved	O
horizontally	O
and	O
vertically	O
though	O
the	O
maze	B-Application
,	O
in	O
order	O
to	O
collect	O
masks	O
.	O
</s>
<s>
In	O
the	O
first	O
level	O
,	O
the	O
only	O
obstacles	O
except	O
for	O
the	O
maze	B-Application
walls	O
themselves	O
,	O
are	O
two	O
types	O
of	O
force	O
field	O
:	O
one	O
of	O
which	O
can	O
only	O
be	O
entered	O
from	O
above	O
or	O
below	O
,	O
and	O
a	O
second	O
which	O
can	O
only	O
be	O
entered	O
from	O
left	O
or	O
right	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
bombs	B-Device
in	O
XOR	B-Application
:	O
"	O
V-bombs	O
"	O
(	O
"	O
vertical	O
"	O
)	O
and	O
"	O
H-bombs	O
"	O
(	O
"	O
horizontal	O
"	O
)	O
.	O
</s>
<s>
V-bombs	O
move	O
left	O
in	O
the	O
same	O
manner	O
as	O
chickens	O
,	O
while	O
H-bombs	O
(	O
shaped	O
like	O
old-fashioned	O
spherical	O
bombs	B-Device
with	O
a	O
burning	O
fuse	O
)	O
fall	O
downwards	O
like	O
fish	O
.	O
</s>
<s>
Like	O
fish	O
and	O
chickens	O
,	O
H-bombs	O
can	O
be	O
pushed	O
left	O
and	O
right	O
,	O
and	O
V-bombs	O
can	O
be	O
pushed	O
up	O
or	O
down	O
,	O
by	O
the	O
player	O
's	O
shield	O
.	O
</s>
<s>
A	O
bomb	B-Device
explodes	O
when	O
it	O
is	O
hit	O
from	O
more	O
than	O
one	O
square	O
away	O
by	O
a	O
fish	O
,	O
a	O
chicken	O
,	O
or	O
another	O
bomb	B-Device
.	O
</s>
<s>
The	O
object	O
hitting	O
the	O
bomb	B-Device
is	O
destroyed	O
,	O
along	O
with	O
anything	O
directly	O
above	O
or	O
below	O
a	O
V-bomb	O
,	O
or	O
to	O
the	O
left	O
or	O
to	O
the	O
right	O
of	O
an	O
H-bomb	O
.	O
</s>
<s>
If	O
one	O
bomb	B-Device
hits	O
another	O
,	O
only	O
the	O
bomb	B-Device
that	O
is	O
hit	O
(	O
the	O
lower	O
or	O
left-hand	O
one	O
)	O
actually	O
detonates	O
.	O
</s>
<s>
Unlike	O
fish	O
and	O
chickens	O
,	O
dolls	O
cannot	O
move	O
on	O
their	O
own	O
,	O
although	O
the	O
player	O
's	O
shields	O
can	O
push	O
them	O
around	O
the	O
maze	B-Application
.	O
</s>
<s>
Dolls	O
cannot	O
detonate	O
bombs	B-Device
or	O
pass	O
through	O
force	O
fields	O
.	O
</s>
<s>
Map	O
sections	O
:	O
these	O
reveal	O
the	O
layout	O
of	O
part	O
the	O
maze	B-Application
to	O
the	O
player	O
.	O
</s>
<s>
Frowning	O
masks	O
:	O
these	O
are	O
switches	O
–	O
collecting	O
(	O
or	O
blowing	O
up	O
)	O
one	O
turns	O
off	O
the	O
lighting	O
,	O
causing	O
the	O
maze	B-Application
walls	O
to	O
become	O
invisible	O
,	O
while	O
collecting	O
another	O
turns	O
the	O
lights	O
back	O
on	O
again	O
.	O
</s>
<s>
Teleportation	O
portals	O
(	O
labelled	O
BMUS	O
,	O
for	O
"	O
Beam	B-Operating_System
Me	I-Operating_System
Up	I-Operating_System
Scotty	I-Operating_System
"	O
,	O
in	O
some	O
versions	O
)	O
:	O
this	O
moves	O
the	O
player	O
's	O
shield	O
to	O
the	O
other	O
teleportation	O
portal	O
within	O
the	O
maze	B-Application
.	O
</s>
<s>
XOR	B-Application
Designer	O
allowed	O
players	O
to	O
design	O
their	O
own	O
levels	O
.	O
</s>
<s>
XOR	B-Application
for	O
Schools	O
included	O
six	O
new	O
mazes	B-Application
and	O
a	O
paper	O
planning	O
sheet	O
,	O
intended	O
to	O
be	O
photocopied	O
by	O
teachers	O
.	O
</s>
<s>
Unauthorized	O
clones	O
have	O
been	O
released	O
for	O
Windows	B-Application
,	O
Macintosh	B-Device
,	O
Linux	B-Application
,	O
RISC	B-Operating_System
OS	I-Operating_System
,	O
the	O
SAM	B-Device
Coupé	I-Device
,	O
the	O
Game	B-Device
Boy	I-Device
Advance	I-Device
,	O
and	O
Uzebox	O
.	O
</s>
