<s>
Caverns	B-Application
of	I-Application
Mars	I-Application
is	O
a	O
vertically	O
scrolling	O
shooter	O
for	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
of	O
home	O
computers	O
.	O
</s>
<s>
It	O
was	O
programmed	O
by	O
Greg	O
Christensen	O
,	O
with	O
some	O
features	O
added	O
by	O
Richard	O
Watts	O
,	O
and	O
published	O
by	O
the	O
Atari	B-Application
Program	I-Application
Exchange	I-Application
(	O
APX	O
)	O
in	O
1981	O
.	O
</s>
<s>
Caverns	B-Application
of	I-Application
Mars	I-Application
became	O
the	O
best	O
selling	O
APX	O
title	O
of	O
all-time	O
and	O
was	O
moved	O
into	O
Atari	O
,	O
Inc.	O
'	O
s	O
official	O
product	O
line	O
,	O
first	O
on	O
diskette	B-Device
and	O
later	O
on	O
cartridge	O
.	O
</s>
<s>
The	O
game	O
is	O
a	O
vertically	O
scrolling	O
variation	O
of	O
Konami	O
's	O
1981	O
arcade	O
game	O
Scramble	B-Application
.	O
</s>
<s>
In	O
Caverns	B-Application
of	I-Application
Mars	I-Application
,	O
the	O
player	O
descends	O
into	O
cave	O
and	O
at	O
the	O
end	O
must	O
retrace	O
their	O
steps	O
back	O
to	O
the	O
top	O
.	O
</s>
<s>
Christensen	O
wrote	O
two	O
less	O
successful	O
sequels	O
,	O
one	O
of	O
which	O
scrolls	O
horizontally	O
and	O
is	O
very	O
similar	O
to	O
Scramble	B-Application
.	O
</s>
<s>
Caverns	B-Application
of	I-Application
Mars	I-Application
is	O
a	O
scrolling	O
shooter	O
similar	O
in	O
concept	O
and	O
visual	O
style	O
to	O
the	O
1981	O
arcade	O
game	O
Scramble	B-Application
.	O
</s>
<s>
Christensen	O
changed	O
the	O
orientation	O
of	O
the	O
caverns	O
from	O
Scramble	B-Application
,	O
having	O
the	O
player	O
fly	O
down	O
into	O
them	O
as	O
opposed	O
to	O
sideways	O
through	O
them	O
.	O
</s>
<s>
Unlike	O
Scramble	B-Application
,	O
rockets	O
in	O
Caverns	B-Application
of	I-Application
Mars	I-Application
remain	O
on	O
the	O
ground	O
.	O
</s>
<s>
Using	O
a	O
joystick	B-Device
,	O
the	O
player	O
controls	O
a	O
ship	O
descending	O
into	O
the	O
tunnels	O
of	O
Mars	B-Application
,	O
firing	O
at	O
targets	O
along	O
the	O
way	O
.	O
</s>
<s>
Greg	O
Christensen	O
,	O
a	O
high-school	O
senior	O
,	O
purchased	O
an	O
Atari	B-Device
800	I-Device
in	O
1981	O
,	O
and	O
created	O
Caverns	O
in	O
"	O
little	O
more	O
than	O
a	O
month	O
and	O
a	O
half	O
"	O
the	O
first	O
significant	O
program	O
he	O
wrote	O
in	O
6502	O
assembly	O
language	O
.	O
</s>
<s>
Fred	O
Thorlin	O
of	O
Atari	B-Application
Program	I-Application
Exchange	I-Application
recalled	O
Caverns	O
arriving	O
at	O
APX	O
:	O
</s>
<s>
Atari	O
licensed	O
the	O
game	O
in	O
early	O
1982	O
for	O
distribution	O
in	O
the	O
main	O
Atari	O
catalog	O
on	O
diskette	B-Device
.	O
</s>
<s>
Computer	O
Gaming	O
World	O
called	O
Caverns	B-Application
of	I-Application
Mars	I-Application
"	O
delightful	O
...	O
addictive	O
and	O
excellently	O
paced	O
"	O
.	O
</s>
<s>
A	O
Creative	B-General_Concept
Computing	I-General_Concept
reviewer	O
opened	O
with	O
"	O
Four	O
minutes	O
later	O
.	O
</s>
<s>
and	O
concluded	O
by	O
noting	O
that	O
"	O
The	O
Caverns	B-Application
of	I-Application
Mars	I-Application
has	O
that	O
indefinable	O
"	O
something	O
"	O
that	O
makes	O
it	O
arcade-quality	O
"	O
.	O
</s>
<s>
Caverns	B-Application
of	I-Application
Mars	I-Application
received	O
a	O
Certificate	O
of	O
Merit	O
in	O
the	O
category	O
of	O
"	O
Best	O
Science	O
Fiction/Fantasy	O
Computer	O
Game	O
"	O
at	O
the	O
4th	O
annual	O
Arkie	O
Awards	O
,	O
</s>
<s>
Christensen	O
followed	O
Caverns	O
in	O
1981	O
with	O
a	O
lesser-known	O
sequel	O
,	O
known	O
originally	O
as	O
Caverns	B-Application
of	I-Application
Mars	I-Application
II	O
.	O
</s>
<s>
This	O
version	O
is	O
very	O
similar	O
to	O
Scramble	B-Application
,	O
scrolling	O
horizontally	O
and	O
with	O
rockets	O
that	O
launch	O
upwards	O
from	O
the	O
ground	O
.	O
</s>
<s>
It	O
would	O
not	O
be	O
published	O
until	O
several	O
years	O
later	O
by	O
Antic	O
Software	O
as	O
Mars	B-Application
Mission	O
II	O
.	O
</s>
<s>
Combining	O
the	O
vertical	O
orientation	O
of	O
the	O
original	O
Caverns	O
with	O
the	O
improved	O
graphics	O
of	O
Caverns	O
II	O
,	O
Phobos	B-Application
was	O
released	O
through	O
APX	O
in	O
1982	O
,	O
although	O
there	O
are	O
other	O
minor	O
modifications	O
as	O
well	O
.	O
</s>
<s>
The	O
system	O
is	O
similar	O
to	O
the	O
one	O
used	O
in	O
Moon	B-Application
Patrol	I-Application
.	O
</s>
<s>
Softline	O
stated	O
that	O
Phobos	B-Application
might	O
disappoint	O
Caverns	B-Application
of	I-Application
Mars	I-Application
players	O
,	O
stating	O
that	O
it	O
was	O
"	O
a	O
reinvention	O
of	O
the	O
wheel	O
"	O
and	O
too	O
easy	O
for	O
them	O
.	O
</s>
<s>
The	O
magazine	O
noted	O
some	O
improvements	O
,	O
such	O
as	O
a	O
pause	B-Device
button	I-Device
and	O
multiple	O
skill	O
levels	O
,	O
but	O
advised	O
that	O
"	O
Mars	B-Application
veterans	O
should	O
wait	O
"	O
.	O
</s>
<s>
In	O
2005	B-Application
,	O
a	O
version	O
of	O
Caverns	B-Application
of	I-Application
Mars	I-Application
was	O
included	O
on	O
the	O
Atari	O
Flashback	O
2	O
classic	O
game	O
console	O
.	O
</s>
<s>
In	O
2023	B-Application
,	O
the	O
game	O
is	O
set	O
for	O
a	O
March	O
release	O
for	O
Microsoft	B-Application
Windows	I-Application
,	O
Nintendo	B-Application
Switch	I-Application
,	O
PlayStation	B-Operating_System
4	I-Operating_System
,	O
PlayStation	B-Device
5	I-Device
,	O
Xbox	B-Device
One	I-Device
and	O
Xbox	B-Device
Series	I-Device
X/S	I-Device
,	O
under	O
the	O
title	O
Caverns	B-Application
of	I-Application
Mars	I-Application
:	O
Recharged	O
.	O
</s>
<s>
Datamost	O
's	O
Cavern	B-Application
Creatures	I-Application
(	O
1983	O
)	O
for	O
the	O
Apple	B-Device
II	I-Device
is	O
very	O
similar	O
.	O
</s>
<s>
Conquest	O
of	O
Mars	B-Application
(	O
2006	O
)	O
for	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
is	O
a	O
direct	O
clone	O
.	O
</s>
