<s>
,	O
known	O
as	O
Digger	O
in	O
North	O
America	O
,	O
is	O
a	O
maze	B-Application
video	I-Application
game	I-Application
created	O
by	O
The	O
University	O
of	O
Tokyo	O
's	O
Theoretical	O
Science	O
Group	O
(	O
TSG	O
)	O
in	O
1979	O
.	O
</s>
<s>
In	O
1980	B-Application
,	O
the	O
arcade	O
game	O
was	O
released	O
in	O
North	O
America	O
as	O
Digger	O
by	O
Sega-Gremlin	O
,	O
with	O
minor	O
changes	O
in	O
appearance	O
.	O
</s>
<s>
The	O
game	O
was	O
a	O
commercial	O
success	O
in	O
Japan	O
,	O
where	O
it	O
was	O
among	O
the	O
top	O
ten	O
highest-grossing	O
arcade	B-Application
games	I-Application
of	I-Application
1979	I-Application
and	O
1980	B-Application
.	O
</s>
<s>
It	O
was	O
an	O
early	O
example	O
of	O
a	O
maze	B-Application
chase	O
game	O
,	O
predating	O
Namco	O
's	O
Pac-Man	B-Application
(	O
1980	B-Application
)	O
.	O
</s>
<s>
It	O
also	O
began	O
a	O
genre	O
of	O
games	O
about	O
digging	O
holes	O
and	O
luring	O
enemies	O
into	O
traps	O
,	O
variously	O
called	O
"	O
trap	O
'	O
em	O
up	O
"	O
or	O
"	O
digging	O
"	O
games	O
,	O
which	O
includes	O
titles	O
such	O
as	O
Space	B-Application
Panic	I-Application
(	O
1980	B-Application
)	O
and	O
Lode	B-Application
Runner	I-Application
(	O
1983	O
)	O
.	O
</s>
<s>
The	O
arcade	O
version	O
uses	O
a	O
Zilog	B-General_Concept
Z80	I-General_Concept
microprocessor	O
,	O
and	O
the	O
arcade	O
system	O
board	O
used	O
is	O
a	O
copied	O
version	O
of	O
the	O
one	O
used	O
by	O
Sega	O
's	O
Head	B-Application
On	I-Application
.	O
</s>
<s>
Heiankyo	B-Application
Alien	I-Application
was	O
created	O
by	O
the	O
Theoretical	O
Science	O
Group	O
,	O
a	O
small	O
group	O
of	O
students	O
at	O
The	O
University	O
of	O
Tokyo	O
in	O
Tokyo	O
,	O
Japan	O
—	O
established	O
in	O
1959	O
,	O
they	O
focused	O
primarily	O
on	O
computer	O
science	O
and	O
soldering	O
,	O
among	O
other	O
similar	O
activities	O
.	O
</s>
<s>
After	O
the	O
Japanese	O
video	O
game	O
market	O
began	O
to	O
"	O
cool	O
off	O
"	O
from	O
the	O
success	O
of	O
Taito	O
's	O
Space	B-Application
Invaders	I-Application
,	O
a	O
column	O
in	O
Weekly	O
Asahi	O
magazine	O
named	O
"	O
Dekigotorogy	O
"	O
appeared	O
,	O
which	O
ran	O
a	O
feature	O
named	O
"	O
In	O
Search	O
of	O
the	O
next	O
Space	B-Application
Invaders	I-Application
"	O
based	O
around	O
the	O
company	O
visiting	O
several	O
different	O
computer	O
clubs	O
across	O
the	O
country	O
in	O
search	O
of	O
potential	O
games	O
to	O
topple	O
the	O
success	O
of	O
Space	B-Application
Invaders	I-Application
.	O
</s>
<s>
Not	O
wanting	O
their	O
idea	O
to	O
go	O
to	O
waste	O
,	O
the	O
group	O
began	O
programming	O
the	O
game	O
on	O
an	O
Apple	B-Device
II	I-Device
computer	O
;	O
however	O
,	O
it	O
suffered	O
from	O
bad	O
optimization	O
and	O
long	O
load	O
times	O
.	O
</s>
<s>
Being	O
presented	O
with	O
the	O
corrected	O
Apple	B-Device
II	I-Device
version	O
,	O
Denki	O
Onkyō	O
approved	O
of	O
the	O
game	O
and	O
hired	O
the	O
group	O
to	O
work	O
for	O
them	O
and	O
make	O
it	O
a	O
full	O
game	O
—	O
prior	O
to	O
this	O
,	O
the	O
Theoretical	O
Science	O
Group	O
briefly	O
visited	O
Namco	O
and	O
Sega	O
,	O
who	O
also	O
expressed	O
interest	O
in	O
the	O
game	O
.	O
</s>
<s>
Programmers	O
coded	O
the	O
game	O
on	O
a	O
Z80	B-General_Concept
assembler	O
,	O
where	O
another	O
would	O
take	O
the	O
code	O
,	O
burn	O
it	O
to	O
a	O
ROM	O
board	O
and	O
test	O
the	O
program	O
to	O
make	O
sure	O
it	O
worked	O
.	O
</s>
<s>
Heiankyo	B-Application
Alien	I-Application
was	O
presented	O
at	O
the	O
1979	O
Amusement	O
Machine	O
Show	O
held	O
in	O
the	O
Harumi	O
area	O
of	O
Chūō	O
,	O
Tokyo	O
.	O
</s>
<s>
The	O
team	O
discovered	O
a	O
bug	O
during	O
its	O
presentation	O
that	O
caused	O
a	O
chunk	O
of	O
the	O
maze	B-Application
to	O
disappear	O
if	O
too	O
many	O
coins	O
were	O
inserted	O
,	O
which	O
allowed	O
enemies	O
to	O
escape	O
the	O
maze	B-Application
and	O
scramble	O
the	O
game	O
's	O
data	O
.	O
</s>
<s>
Meldac	O
released	O
a	O
Game	B-Device
Boy	I-Device
version	O
of	O
the	O
game	O
in	O
Japan	O
and	O
North	O
America	O
in	O
1990	O
.	O
</s>
<s>
The	O
game	O
was	O
also	O
ported	O
to	O
the	O
Super	B-Application
Famicom	I-Application
by	O
Nihon	O
Bussan	O
in	O
1995	O
as	O
Nichibutsu	B-Application
Arcade	I-Application
Classics	I-Application
2	I-Application
:	I-Application
Heiankyo	I-Application
Alien	I-Application
.	O
</s>
<s>
2017	O
saw	O
two	O
further	O
ports	O
of	O
the	O
game	O
:	O
NEO	O
Heiankyo	B-Application
Alien	I-Application
by	O
Columbus	O
Circle	O
for	O
Famicom	O
and	O
an	O
official	O
remaster	O
Heiankyo	B-Application
Alien	I-Application
3671	O
was	O
released	O
by	O
Mindware	O
on	O
Steam	B-Application
.	O
</s>
<s>
Heiankyo	B-Application
Alien	I-Application
was	O
widely	O
successful	O
when	O
it	O
was	O
first	O
released	O
,	O
being	O
praised	O
for	O
its	O
originality	O
and	O
element	O
of	O
strategy	O
.	O
</s>
<s>
The	O
Japanese	O
manga	O
Game	O
Center	O
Arashi	O
,	O
which	O
featured	O
a	O
story	O
based	O
on	O
Heiankyo	B-Application
Alien	I-Application
,	O
is	O
believed	O
to	O
have	O
attributed	O
to	O
the	O
game	O
's	O
success	O
due	O
to	O
its	O
usage	O
of	O
terminology	O
and	O
strategies	O
made	O
by	O
other	O
players	O
—	O
author	O
Misuru	O
Sugaya	O
has	O
stated	O
that	O
Heiankyo	B-Application
Alien	I-Application
remains	O
his	O
favorite	O
game	O
,	O
and	O
claims	O
to	O
play	O
it	O
regularly	O
on	O
his	O
computer	O
.	O
</s>
<s>
In	O
Japan	O
,	O
Heiankyo	B-Application
Alien	I-Application
was	O
among	O
the	O
top	O
ten	O
highest-grossing	O
arcade	B-Application
games	I-Application
of	I-Application
1979	I-Application
.	O
</s>
<s>
The	O
following	O
year	O
,	O
it	O
was	O
the	O
seventh	O
highest-grossing	O
arcade	B-Application
game	I-Application
of	I-Application
1980	I-Application
.	O
</s>
<s>
The	O
Game	B-Device
Boy	I-Device
release	O
was	O
more	O
negatively	O
received	O
.	O
</s>
<s>
Taito	O
produced	O
a	O
version	O
with	O
a	O
light-blue	O
background	O
that	O
recycled	O
many	O
sound	O
effects	O
from	O
Head	B-Application
On	I-Application
.	O
</s>
<s>
Heiankyo	B-Application
Alien	I-Application
was	O
an	O
early	O
example	O
of	O
a	O
maze	B-Application
chase	O
game	O
,	O
predating	O
Namco	O
's	O
Pac-Man	B-Application
(	O
1980	B-Application
)	O
.	O
</s>
<s>
Heiankyo	B-Application
Alien	I-Application
also	O
began	O
a	O
genre	O
about	O
digging	O
holes	O
and	O
luring	O
enemies	O
into	O
traps	O
,	O
variously	O
called	O
"	O
trap	O
'	O
em	O
up	O
"	O
or	O
"	O
digging	O
"	O
games	O
.	O
</s>
<s>
It	O
includes	O
Space	B-Application
Panic	I-Application
(	O
1980	B-Application
)	O
and	O
its	O
clones	O
(	O
e.g.	O
</s>
<s>
Apple	B-Application
Panic	I-Application
)	O
,	O
which	O
also	O
feature	O
trappable	O
aliens	O
,	O
as	O
well	O
as	O
Lode	B-Application
Runner	I-Application
(	O
1983	O
)	O
,	O
where	O
enemies	O
are	O
human	O
guards	O
.	O
</s>
<s>
Doraemon	B-Application
Meikyū	O
Daisakusen	O
(	O
1989	O
)	O
and	O
Boomer	B-Application
's	I-Application
Adventure	I-Application
in	I-Application
ASMIK	I-Application
World	I-Application
(	O
1989	O
)	O
are	O
later	O
examples	O
.	O
</s>
<s>
The	O
VIC-20	B-Device
cartridge	O
game	O
Alien	O
appears	O
to	O
be	O
a	O
direct	O
clone	O
of	O
Heiankyo	B-Application
Alien	I-Application
.	O
</s>
