<s>
Originally	O
released	O
for	O
the	O
NEC	B-Device
PC-8801	I-Device
,	O
it	O
was	O
ported	O
to	O
other	O
platforms	O
,	O
including	O
the	O
Family	O
Computer	O
.	O
</s>
<s>
Door	B-Application
Door	I-Application
was	O
designed	O
and	O
programmed	O
by	O
Koichi	O
Nakamura	O
,	O
known	O
as	O
one	O
of	O
the	O
creators	O
of	O
Dragon	B-Application
Quest	I-Application
.	O
</s>
<s>
Door	B-Application
Door	I-Application
was	O
a	O
critical	O
and	O
commercial	O
success	O
—	O
the	O
PC-8801	B-Device
port	O
alone	O
had	O
sold	O
200,000	O
copies	O
,	O
and	O
is	O
considered	O
a	O
classic	O
title	O
for	O
the	O
Famicom	O
.	O
</s>
<s>
Chun	O
is	O
relentlessly	O
pursued	O
by	O
a	O
quartet	O
of	O
aliens	O
traveling	O
in	O
deterministic	B-General_Concept
algorithm	I-General_Concept
paths	O
.	O
</s>
<s>
Points	O
are	O
awarded	O
for	O
trapping	O
aliens	O
behind	O
doors	O
(	O
with	O
extra	O
points	O
going	O
to	O
players	O
who	O
corral	O
multiple	O
aliens	O
behind	O
one	O
door	O
)	O
and	O
collecting	O
confectionery	O
that	O
intermittently	O
appear	O
and	O
disappear	O
on	O
the	O
playing	O
screen	O
,	O
which	O
include	O
a	O
striped	O
piece	O
of	O
candy	O
,	O
an	O
ice	O
pop	O
,	O
a	O
lollipop	B-Application
,	O
a	O
bowl	O
of	O
ice	O
cream	O
,	O
a	O
slice	O
of	O
cake	O
,	O
and	O
a	O
Mahjong	B-Application
tile	O
.	O
</s>
<s>
This	O
is	O
a	O
unique	O
trait	O
of	O
Door	B-Application
Door	I-Application
as	O
most	O
games	O
prevent	O
such	O
a	O
scenario	O
with	O
a	O
time	O
limit	O
(	O
such	O
as	O
Super	B-Application
Mario	I-Application
Bros	I-Application
.	I-Application
)	O
or	O
physical	O
restriction	O
(	O
such	O
as	O
Tetris	B-Device
)	O
.	O
</s>
<s>
There	O
is	O
no	O
ending	O
in	O
Door	B-Application
Door	I-Application
;	O
after	O
completing	O
the	O
final	O
level	O
,	O
the	O
game	O
simply	O
restarts	O
at	O
the	O
first	O
level	O
,	O
although	O
the	O
player	O
's	O
accumulated	O
score	O
is	O
retained	O
for	O
the	O
player	O
to	O
build	O
higher	O
through	O
continued	O
play	O
.	O
</s>
<s>
Three	O
hundred	O
programs	O
were	O
entered	O
into	O
the	O
contest	O
,	O
and	O
the	O
first	O
prize	O
went	O
to	O
programming	O
prodigy	O
and	O
high	O
school	O
student	O
Koichi	O
Nakamura	O
for	O
his	O
puzzle	O
game	O
,	O
Door	B-Application
Door	I-Application
.	O
</s>
<s>
Yuji	O
Horii	O
placed	O
in	O
the	O
finals	O
of	O
the	O
same	O
contest	O
with	O
a	O
computer	O
tennis	O
game	O
;	O
both	O
were	O
subsequently	O
hired	O
by	O
Enix	O
and	O
the	O
rights	O
to	O
Door	B-Application
Door	I-Application
became	O
property	O
of	O
Enix	O
.	O
</s>
<s>
Enix	O
published	O
the	O
game	O
on	O
a	O
wide	O
range	O
of	O
Japanese	O
computers	O
,	O
including	O
NEC	O
's	O
PC-8801	B-Device
,	O
Fujitsu	O
's	O
FM-7	B-Device
,	O
and	O
Sharp	O
's	O
MZ-2000	O
.	O
</s>
<s>
With	O
sales	O
exceeding	O
200,000	O
copies	O
,	O
Door	B-Application
Door	I-Application
was	O
a	O
huge	O
success	O
.	O
</s>
<s>
In	O
1986	O
,	O
Enix	O
's	O
third	O
Famicom	O
production	O
and	O
first	O
role-playing	O
video	O
game	O
made	O
Horii	O
and	O
Nakamura	O
household	O
names	O
in	O
Japan	O
:	O
Dragon	B-Application
Quest	I-Application
.	O
</s>
<s>
In	O
1984	O
,	O
Nakamura	O
created	O
a	O
relatively	O
exclusive	O
contracting	O
company	O
,	O
christened	O
Chunsoft	O
in	O
honor	O
of	O
Door	B-Application
Door	I-Application
diminutive	O
hero	O
.	O
</s>
<s>
An	O
expanded	O
version	O
of	O
the	O
game	O
,	O
branded	O
Door	B-Application
Door	I-Application
mkII	I-Application
,	O
was	O
released	O
two	O
years	O
after	O
the	O
original	O
in	O
February	O
1985	O
.	O
</s>
<s>
The	O
game	O
was	O
ported	O
to	O
MSX	B-Operating_System
computers	O
,	O
NEC	O
's	O
PC-6001	B-Device
,	O
PC-6001mkII	O
,	O
PC-6601	O
,	O
PC-8801	B-Device
,	O
PC-8801mkII	O
,	O
and	O
PC-8801mkIISR	O
models	O
,	O
Sharp	O
's	O
MZ-2000	O
,	O
and	O
Fujitsu	O
's	O
FM-7	B-Device
.	O
</s>
<s>
Encouraged	O
by	O
the	O
rapidly	O
increasing	O
popularity	O
of	O
video	O
game	O
consoles	O
in	O
Japan	O
,	O
Enix	O
also	O
ported	O
Door	B-Application
Door	I-Application
to	O
Nintendo	O
's	O
Famicom	O
.	O
</s>
<s>
In	O
March	O
2004	O
,	O
Chunsoft	O
celebrated	O
their	O
20th	O
anniversary	O
by	O
releasing	O
a	O
version	O
of	O
Door	B-Application
Door	I-Application
for	O
Japanese	O
mobile	O
phone	O
networks	O
.	O
</s>
<s>
A	O
faithful	O
reproduction	O
of	O
the	O
Famicom	O
version	O
,	O
the	O
application	O
is	O
available	O
for	O
the	O
NTT	O
DoCoMo	O
FOMA	O
505i	O
and	O
900i	O
series	O
phones	O
,	O
and	O
can	O
be	O
downloaded	B-Application
from	O
i-chunsoft	O
for	O
¥300	O
per	O
month	O
.	O
</s>
<s>
To	O
the	O
right	O
is	O
a	O
table	O
of	O
all	O
licensed	O
ports	O
of	O
Door	B-Application
Door	I-Application
.	O
</s>
<s>
A	O
modified	O
version	O
featuring	O
Mean	O
Clean	O
( エコ吉	O
,	O
eco	O
kichi	O
in	O
Japanese	O
)	O
as	O
the	O
main	O
protagonist	O
is	O
also	O
featured	O
in	O
the	O
2008	O
visual	O
novel	O
428	B-Application
:	I-Application
Shibuya	I-Application
Scramble	I-Application
as	O
an	O
unlockable	O
bonus	O
.	O
</s>
