<s>
is	O
a	O
1992	O
platform	O
game	O
developed	O
by	O
Sega	O
Technical	O
Institute	O
(	O
STI	O
)	O
for	O
the	O
Sega	B-Operating_System
Genesis	I-Operating_System
.	O
</s>
<s>
It	O
follows	O
Sonic	B-Application
as	O
he	O
attempts	O
to	O
stop	O
Doctor	O
Robotnik	O
from	O
stealing	O
the	O
Chaos	O
Emeralds	O
to	O
power	O
his	O
space	O
station	O
.	O
</s>
<s>
Like	O
the	O
first	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
(	O
1991	O
)	O
,	O
players	O
traverse	O
side-scrolling	O
levels	O
at	O
high	O
speeds	O
while	O
collecting	O
rings	O
,	O
defeating	O
enemies	O
,	O
and	O
fighting	O
bosses	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
introduces	O
Sonic	B-Application
's	O
sidekick	B-Application
Miles	O
"	O
Tails	O
"	O
Prower	O
and	O
features	O
faster	O
gameplay	O
,	O
larger	O
levels	O
,	O
a	O
multiplayer	O
mode	O
,	O
and	O
special	O
stages	O
featuring	O
pre-rendered	O
3D	O
graphics	O
.	O
</s>
<s>
After	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
greatly	O
increased	O
the	O
popularity	O
of	O
the	O
Genesis	O
in	O
North	O
America	O
,	O
Sega	O
directed	O
STI	O
founder	O
Mark	O
Cerny	O
to	O
start	O
Sonic	B-Application
2	I-Application
in	O
November	O
1991	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
was	O
intended	O
to	O
be	O
faster	O
and	O
more	O
ambitious	O
than	O
the	O
first	O
game	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
was	O
widely	O
anticipated	O
,	O
and	O
Sega	O
backed	O
it	O
with	O
an	O
aggressive	O
marketing	O
campaign	O
.	O
</s>
<s>
Critics	O
considered	O
Sonic	B-Application
2	I-Application
an	O
improvement	O
over	O
the	O
first	O
game	O
and	O
praised	O
the	O
visuals	O
,	O
level	O
design	O
,	O
gameplay	O
,	O
and	O
music	O
,	O
though	O
the	O
low	O
difficulty	O
level	O
and	O
similarities	O
to	O
its	O
predecessor	O
were	O
criticized	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
broke	O
video	O
game	O
sales	O
records	O
and	O
became	O
the	O
fastest-selling	O
game	O
at	O
the	O
time	O
,	O
grossing	O
over	O
.	O
</s>
<s>
With	O
six	O
million	O
copies	O
sold	O
worldwide	O
,	O
it	O
is	O
the	O
second-bestselling	B-Application
Genesis	I-Application
game	I-Application
behind	O
the	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
solidified	O
Sonic	B-Application
as	O
a	O
major	O
franchise	O
and	O
helped	O
keep	O
Sega	O
competitive	O
during	O
the	O
console	O
wars	O
of	O
the	O
16-bit	B-Application
era	I-Application
in	O
the	O
early	O
1990s	O
.	O
</s>
<s>
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
and	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
followed	O
in	O
1994	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
has	O
been	O
rereleased	O
on	O
various	O
platforms	O
via	O
compilations	O
and	O
emulation	O
,	O
and	O
a	O
remake	O
for	O
iOS	B-Application
and	O
Android	B-Application
devices	O
,	O
developed	O
using	O
the	O
Retro	B-Application
Engine	I-Application
,	O
was	O
released	O
in	O
December	O
2013	O
.	O
</s>
<s>
A	O
number	O
of	O
Sonic	B-Application
2	I-Application
prototypes	B-Application
have	O
leaked	O
since	O
the	O
release	O
;	O
the	O
first	O
,	O
discovered	O
in	O
1999	O
,	O
played	O
a	O
significant	O
role	O
in	O
the	O
development	O
of	O
a	O
video	O
game	O
research	O
scene	O
.	O
</s>
<s>
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
is	O
a	O
side-scrolling	O
platform	O
game	O
.	O
</s>
<s>
It	O
features	O
a	O
story	O
similar	O
to	O
the	O
first	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
(	O
1991	O
)	O
:	O
Doctor	O
Robotnik	O
,	O
a	O
mad	O
scientist	O
,	O
seeks	O
the	O
Chaos	O
Emeralds	O
to	O
power	O
his	O
space	O
station	O
,	O
the	O
Death	O
Egg	O
,	O
and	O
traps	O
the	O
animal	O
inhabitants	O
of	O
West	O
Island	O
in	O
aggressive	O
robots	O
.	O
</s>
<s>
As	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
,	O
the	O
player	O
embarks	O
on	O
a	O
journey	O
to	O
collect	O
the	O
Chaos	O
Emeralds	O
and	O
stop	O
Robotnik	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
introduces	O
the	O
spin	O
dash	O
,	O
which	O
allows	O
the	O
player	O
to	O
curl	O
while	O
stationary	O
for	O
a	O
speed	O
boost	O
,	O
and	O
Miles	O
"	O
Tails	O
"	O
Prower	O
,	O
a	O
fox	O
with	O
two	O
tails	O
who	O
acts	O
as	O
Sonic	B-Application
's	O
sidekick	B-Application
.	O
</s>
<s>
In	O
the	O
default	O
single-player	O
game	O
mode	O
,	O
the	O
player	O
controls	O
Sonic	B-Application
and	O
Tails	O
simultaneously	O
;	O
a	O
second	O
player	O
can	O
join	O
in	O
at	O
any	O
time	O
and	O
control	O
Tails	O
separately	O
.	O
</s>
<s>
The	O
player	O
can	O
also	O
choose	O
to	O
play	O
as	O
Sonic	B-Application
or	O
Tails	O
individually	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
features	O
twice	O
as	O
many	O
unique	O
level	O
themes	O
compared	O
to	O
the	O
first	O
game	O
,	O
and	O
most	O
levels	O
end	O
after	O
two	O
acts	O
rather	O
than	O
three	O
.	O
</s>
<s>
The	O
player	O
starts	O
with	O
three	O
lives	O
,	O
which	O
they	O
lose	O
if	O
they	O
are	O
hit	O
without	O
a	O
ring	O
,	O
fall	O
down	O
a	O
pit	O
,	O
get	O
crushed	O
,	O
drown	O
,	O
or	O
reach	O
the	O
10-minute	O
time	O
limit	O
;	O
they	O
receive	O
a	O
game	B-Application
over	I-Application
if	O
they	O
run	O
out	O
.	O
</s>
<s>
When	O
all	O
the	O
Chaos	O
Emeralds	O
have	O
been	O
collected	O
,	O
Sonic	B-Application
can	O
transform	O
into	O
Super	O
Sonic	B-Application
by	O
collecting	O
50	O
rings	O
.	O
</s>
<s>
Super	O
Sonic	B-Application
is	O
nearly	O
invincible	O
,	O
runs	O
faster	O
,	O
and	O
jumps	O
farther	O
,	O
but	O
loses	O
one	O
ring	O
per	O
second	O
and	O
reverts	O
to	O
normal	O
when	O
his	O
rings	O
are	O
depleted	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
introduces	O
a	O
multiplayer	O
game	O
mode	O
where	O
two	O
players	O
compete	O
against	O
each	O
other	O
in	O
a	O
split-screen	O
race	O
across	O
three	O
levels	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
was	O
released	O
in	O
1994	O
,	O
two	O
years	O
after	O
Sonic	B-Application
2	I-Application
.	O
</s>
<s>
The	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
game	B-Protocol
cartridge	I-Protocol
features	O
a	O
"	O
lock-on	O
"	O
adapter	O
that	O
allows	O
players	O
to	O
insert	O
other	O
Sega	B-Operating_System
Genesis	I-Operating_System
cartridges	B-Protocol
.	O
</s>
<s>
Attaching	O
Sonic	B-Application
2	I-Application
unlocks	O
Knuckles	O
the	O
Echidna	O
in	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
,	O
a	O
variation	O
of	O
Sonic	B-Application
2	I-Application
in	O
which	O
the	O
player	O
controls	O
the	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
(	O
1994	O
)	O
character	O
Knuckles	O
the	O
Echidna	O
.	O
</s>
<s>
The	O
level	O
design	O
is	O
identical	O
,	O
but	O
Knuckles	O
can	O
glide	O
and	O
climb	O
walls	O
,	O
allowing	O
him	O
access	O
to	O
areas	O
inaccessible	O
to	O
Sonic	B-Application
or	O
Tails	O
.	O
</s>
<s>
The	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
was	O
published	O
by	O
Sega	O
for	O
the	O
Sega	B-Operating_System
Genesis	I-Operating_System
in	O
June	O
1991	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
Sonic	B-Application
Team	O
,	O
led	O
by	O
programmer	O
Yuji	O
Naka	O
,	O
artist	O
Naoto	O
Ohshima	O
,	O
and	O
designer	O
Hirokazu	O
Yasuhara	O
.	O
</s>
<s>
Sonic	B-Application
greatly	O
increased	O
the	O
Genesis	O
's	O
popularity	O
in	O
North	O
America	O
and	O
is	O
credited	O
with	O
helping	O
Sega	O
gain	O
65%	O
of	O
the	O
market	O
share	O
against	O
then-industry	O
leader	O
Nintendo	O
,	O
making	O
Sega	O
a	O
formidable	O
competitor	O
.	O
</s>
<s>
The	O
success	O
meant	O
that	O
a	O
sequel	O
was	O
inevitable	O
,	O
but	O
shortly	O
after	O
the	O
release	O
,	O
Naka	O
quit	O
Sega	O
due	O
to	O
disagreements	O
over	O
his	O
salary	O
,	O
dissatisfaction	O
over	O
the	O
time	O
and	O
effort	O
it	O
had	O
taken	O
to	O
finish	O
Sonic	B-Application
,	O
and	O
a	O
lack	O
of	O
support	O
from	O
management	O
.	O
</s>
<s>
During	O
the	O
development	O
of	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
,	O
Mark	O
Cerny	O
established	O
Sega	O
Technical	O
Institute	O
(	O
STI	O
)	O
in	O
California	O
.	O
</s>
<s>
Yasuhara	O
and	O
other	O
members	O
of	O
the	O
Sonic	B-Application
development	O
team	O
joined	O
Naka	O
,	O
but	O
Ohshima	O
stayed	O
in	O
Japan	O
to	O
work	O
on	O
Sonic	B-Application
CD	I-Application
(	O
1993	O
)	O
.	O
</s>
<s>
In	O
September	O
1991	O
,	O
Cerny	O
pitched	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
as	O
STI	O
's	O
project	O
for	O
the	O
1992	O
Christmas	O
and	O
holiday	O
shopping	O
season	O
—	O
giving	O
the	O
team	O
11	O
months	O
of	O
development	O
—	O
but	O
Sega	O
of	O
America	O
considered	O
it	O
too	O
soon	O
for	O
a	O
sequel	O
and	O
was	O
still	O
unconfident	O
in	O
the	O
Sonic	B-Application
character	O
.	O
</s>
<s>
STI	O
explored	O
other	O
concepts	O
,	O
but	O
in	O
November	O
,	O
Sega	O
reversed	O
course	O
and	O
told	O
Cerny	O
that	O
it	O
needed	O
Sonic	B-Application
2	I-Application
for	O
the	O
1992	O
holiday	O
season	O
.	O
</s>
<s>
Cerny	O
said	O
that	O
this	O
did	O
not	O
cost	O
STI	O
any	O
game	O
ideas	O
since	O
they	O
had	O
yet	O
to	O
come	O
up	O
with	O
one	O
on	O
par	O
with	O
Sonic	B-Application
,	O
but	O
they	O
lost	O
two	O
months	O
of	O
development	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
development	O
team	O
was	O
much	O
larger	O
than	O
the	O
first	O
game	O
's	O
and	O
consisted	O
of	O
both	O
American	O
and	O
Japanese	O
developers	O
,	O
although	O
the	O
majority	O
of	O
the	O
team	O
was	O
Japanese	O
.	O
</s>
<s>
Sega	O
of	O
America	O
marketing	O
director	O
Al	O
Nilsen	O
said	O
that	O
STI	O
wanted	O
"	O
to	O
go	O
all	O
out	O
"	O
to	O
ensure	O
Sonic	B-Application
2	I-Application
would	O
be	O
as	O
successful	O
as	O
the	O
original	O
Sonic	B-Application
,	O
since	O
sequels	O
were	O
generally	O
not	O
well	O
regarded	O
.	O
</s>
<s>
STI	O
brainstormed	O
various	O
ideas	O
to	O
improve	O
the	O
first	O
game	O
's	O
formula	O
,	O
beginning	O
with	O
making	O
Sonic	B-Application
faster	O
.	O
</s>
<s>
In	O
the	O
first	O
game	O
,	O
the	O
developers	O
limited	O
Sonic	B-Application
with	O
a	O
cap	O
that	O
prevented	O
players	O
from	O
running	O
at	O
his	O
maximum	O
possible	O
speed	O
;	O
STI	O
lifted	O
the	O
cap	O
for	O
Sonic	B-Application
2	I-Application
.	O
</s>
<s>
Yasuhara	O
had	O
ambitious	O
plans	O
for	O
Sonic	B-Application
2	I-Application
and	O
designed	O
it	O
with	O
blue	O
sky	O
 '	O
ideas	O
"	O
.	O
</s>
<s>
Assuming	O
STI	O
had	O
two	O
years	O
of	O
development	O
,	O
he	O
conceived	O
a	O
plot	O
in	O
which	O
Robotnik	O
took	O
over	O
the	O
world	O
and	O
Sonic	B-Application
used	O
time	O
travel	O
to	O
stop	O
him	O
.	O
</s>
<s>
The	O
plot	O
was	O
scrapped	O
,	O
but	O
many	O
of	O
Sonic	B-Application
2	I-Application
levels	O
were	O
taken	O
from	O
it	O
;	O
for	O
example	O
,	O
Hill	O
Top	O
Zone	O
(	O
which	O
features	O
dinosaur	O
enemies	O
)	O
was	O
intended	O
to	O
be	O
a	O
past	O
version	O
of	O
Green	O
Hill	O
Zone	O
,	O
while	O
Chemical	O
Plant	O
and	O
Casino	O
Night	O
came	O
from	O
the	O
Robotnik-ruled	O
future	O
.	O
</s>
<s>
He	O
was	O
inspired	O
to	O
design	O
Casino	O
Night	O
because	O
he	O
found	O
Sonic	B-Application
springs	O
similar	O
to	O
the	O
gimmicks	O
of	O
pinball	B-Application
tables	O
,	O
while	O
Sky	O
Chase	O
—	O
which	O
features	O
Sonic	B-Application
riding	O
a	O
biplane	O
as	O
he	O
attempts	O
to	O
reach	O
Robotnik	O
's	O
base	O
—	O
was	O
inspired	O
by	O
Hayao	O
Miyazaki	O
's	O
anime	O
Future	O
Boy	O
Conan	O
(	O
1978	O
)	O
.	O
</s>
<s>
Naka	O
suggested	O
the	O
second	O
character	O
be	O
endearing	O
,	O
similar	O
to	O
the	O
kitsune	O
from	O
Urusei	O
Yatsura	O
,	O
and	O
beginner-oriented	O
rather	O
than	O
Sonic	B-Application
's	O
rival	O
.	O
</s>
<s>
An	O
internal	O
contest	O
was	O
held	O
to	O
determine	O
the	O
new	O
character	O
,	O
and	O
the	O
winning	O
design	O
was	O
lead	O
artist	O
Yasushi	O
Yamaguchi	O
's	O
fox	O
,	O
which	O
he	O
named	O
Miles	O
Prower	O
(	O
a	O
pun	B-Application
on	O
"	O
miles	O
per	O
hour	O
"	O
)	O
.	O
</s>
<s>
STI	O
wanted	O
the	O
character	O
to	O
appeal	O
to	O
Japanese	O
audiences	O
,	O
and	O
Yamaguchi	O
gave	O
him	O
two	O
tails	O
—	O
inspired	O
by	O
the	O
Phantasy	B-Application
Star	I-Application
character	O
Myau	O
—	O
to	O
make	O
the	O
design	O
more	O
impactful	O
.	O
</s>
<s>
Tails	O
was	O
implemented	O
using	O
an	O
artificial	B-Application
intelligence	I-Application
routine	O
that	O
allowed	O
him	O
to	O
mimic	O
Sonic	B-Application
's	O
movements	O
.	O
</s>
<s>
He	O
was	O
also	O
used	O
in	O
the	O
multiplayer	O
mode	O
,	O
something	O
that	O
Naka	O
had	O
attempted	O
to	O
implement	O
late	O
in	O
development	O
of	O
the	O
original	O
Sonic	B-Application
.	O
</s>
<s>
The	O
multiplayer	O
mode	O
was	O
one	O
of	O
Naka	O
's	O
primary	O
motivations	O
to	O
develop	O
Sonic	B-Application
2	I-Application
,	O
since	O
he	O
felt	O
multiplayer	O
games	O
were	O
more	O
fun	O
.	O
</s>
<s>
The	O
artists	O
had	O
to	O
deal	O
with	O
palette	B-Data_Structure
limitations	O
,	O
as	O
only	O
64	O
colors	O
could	O
be	O
displayed	O
on-screen	O
.	O
</s>
<s>
The	O
special	O
stages	O
,	O
designed	O
by	O
Shinobi	B-Application
(	O
1987	O
)	O
director	O
Yutaka	O
Sugano	O
,	O
were	O
created	O
from	O
pre-rendered	O
3D	O
polygons	O
,	O
video	O
of	O
which	O
was	O
compressed	O
and	O
halved	O
vertically	O
and	O
horizontally	O
to	O
fit	O
in	O
the	O
game	B-Protocol
cartridge	I-Protocol
.	O
</s>
<s>
In	O
retrospect	O
,	O
he	O
felt	O
the	O
stages	O
were	O
visually	O
impressive	O
but	O
did	O
not	O
have	O
as	O
much	O
gameplay	O
depth	O
as	O
the	O
original	O
Sonic	B-Application
special	O
stages	O
,	O
which	O
featured	O
Sonic	B-Application
navigating	O
a	O
rotating	O
maze	O
.	O
</s>
<s>
Further	O
complicating	O
this	O
was	O
STI	O
's	O
involvement	O
with	O
the	O
Sonic	B-Application
franchise	I-Application
and	O
Naka	O
's	O
desire	O
to	O
oversee	O
development	O
personally	O
,	O
as	O
well	O
as	O
Sega	O
of	O
America	O
's	O
initial	O
hesitation	O
to	O
assist	O
given	O
their	O
lack	O
of	O
confidence	O
in	O
the	O
Sonic	B-Application
character	O
.	O
</s>
<s>
Yoshii	O
was	O
installed	O
as	O
the	O
temporary	O
head	O
of	O
STI	O
and	O
was	O
credited	O
as	O
Sonic	B-Application
2	I-Application
director	O
.	O
</s>
<s>
He	O
said	O
that	O
the	O
situation	O
was	O
severe	O
because	O
Sega	O
of	O
America	O
was	O
"	O
betting	O
everything	O
"	O
on	O
Sonic	B-Application
2	I-Application
,	O
but	O
the	O
STI	O
staff	O
did	O
not	O
display	O
any	O
stress	O
and	O
remained	O
optimistic	O
that	O
the	O
project	O
would	O
be	O
finished	O
.	O
</s>
<s>
Nilsen	O
said	O
Sonic	B-Application
2	I-Application
"	O
probably	O
could	O
have	O
been	O
three	O
times	O
the	O
size	O
if	O
we	O
left	O
in	O
everything	O
that	O
was	O
there	O
.	O
</s>
<s>
It	O
was	O
planned	O
as	O
a	O
secret	O
stage	O
accessed	O
by	O
collecting	O
Chaos	O
Emeralds	O
;	O
according	O
to	O
Naka	O
,	O
it	O
would	O
explain	O
the	O
origin	O
of	O
the	O
Chaos	O
Emeralds	O
and	O
grant	O
Sonic	B-Application
his	O
Super	O
Sonic	B-Application
powers	O
.	O
</s>
<s>
Though	O
Hidden	O
Palace	O
was	O
one	O
of	O
the	O
first	O
levels	O
implemented	O
,	O
work	O
on	O
it	O
stopped	O
in	O
mid-1992	O
,	O
and	O
it	O
was	O
removed	O
shortly	O
before	O
completion	O
for	O
a	O
lack	O
of	O
time	O
and	O
cartridge	B-Protocol
space	O
.	O
</s>
<s>
One	O
scrapped	O
level	O
,	O
Genocide	B-Protocol
City	O
,	O
was	O
renamed	O
Cyber	O
City	O
because	O
the	O
Japanese	O
developers	O
had	O
not	O
understood	O
the	O
negative	O
connotations	O
of	O
the	O
word	O
genocide	B-Protocol
.	O
</s>
<s>
Its	O
level	O
layout	O
was	O
used	O
in	O
the	O
Metropolis	B-Application
Zone	I-Application
level	O
.	O
</s>
<s>
As	O
with	O
the	O
first	O
game	O
,	O
Sonic	B-Application
2	I-Application
soundtrack	O
was	O
composed	O
by	O
Masato	O
Nakamura	O
,	O
a	O
member	O
of	O
the	O
J-pop	O
band	O
Dreams	O
Come	O
True	O
.	O
</s>
<s>
Nakamura	O
became	O
famous	O
in	O
Japan	O
after	O
the	O
release	O
of	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
and	O
increased	O
his	O
asking	O
price	O
considerably	O
.	O
</s>
<s>
He	O
treated	O
Sonic	B-Application
2	I-Application
like	O
a	O
film	O
and	O
attempted	O
to	O
reflect	O
the	O
atmosphere	O
he	O
felt	O
in	O
the	O
concept	O
art	O
.	O
</s>
<s>
Nakamura	O
composed	O
Sonic	B-Application
2	I-Application
simultaneously	O
with	O
the	O
1992	O
Dreams	O
Come	O
True	O
album	O
The	O
Swinging	O
Star	O
.	O
</s>
<s>
As	O
a	O
gift	O
to	O
the	O
developers	O
,	O
he	O
produced	O
an	O
alternate	O
version	O
of	O
the	O
Sonic	B-Application
2	I-Application
ending	O
theme	O
,	O
"	O
Sweet	O
Sweet	O
Sweet	O
"	O
,	O
for	O
the	O
album	O
.	O
</s>
<s>
Since	O
Sonic	B-Application
2	I-Application
was	O
more	O
technically	O
advanced	O
than	O
its	O
predecessor	O
,	O
Nakamura	O
"	O
wanted	O
to	O
create	O
music	O
that	O
showed	O
progress	O
...	O
</s>
<s>
Sonic	B-Application
2	I-Application
did	O
not	O
become	O
playable	O
from	O
start	O
to	O
finish	O
until	O
the	O
last	O
48	O
hours	O
of	O
development	O
,	O
in	O
September	O
1992	O
.	O
</s>
<s>
The	O
team	O
planned	O
to	O
use	O
a	O
4MiB	O
cartridge	B-Protocol
,	O
the	O
same	O
cartridge	B-Protocol
size	O
as	O
the	O
first	O
game	O
,	O
but	O
STI	O
ran	O
out	O
of	O
space	O
towards	O
the	O
end	O
of	O
development	O
.	O
</s>
<s>
In	O
total	O
,	O
over	O
100	O
people	O
worked	O
on	O
Sonic	B-Application
2	I-Application
and	O
the	O
main	O
team	O
comprised	O
20	O
developers	O
.	O
</s>
<s>
Yoshii	O
said	O
that	O
Sonic	B-Application
2	I-Application
would	O
not	O
have	O
been	O
ready	O
for	O
release	O
without	O
Sega	O
of	O
America	O
's	O
bug-checking	O
process	O
.	O
</s>
<s>
STI	O
videotaped	O
testers	O
 '	O
gameplay	O
so	O
the	O
developers	O
could	O
easily	O
locate	O
bugs	B-Error_Name
.	O
</s>
<s>
Around	O
50	O
developers	O
worked	O
as	O
bug	B-Error_Name
checkers	O
,	O
and	O
the	O
process	O
took	O
two	O
to	O
three	O
weeks	O
.	O
</s>
<s>
Yoshii	O
felt	O
that	O
despite	O
the	O
staff	O
conflicts	O
,	O
the	O
bug-checking	O
made	O
developing	O
Sonic	B-Application
2	I-Application
in	O
the	O
US	O
worth	O
it	O
,	O
as	O
Sega	O
of	O
America	O
's	O
process	O
was	O
much	O
more	O
thorough	O
than	O
the	O
one	O
in	O
Japan	O
.	O
</s>
<s>
When	O
Sonic	B-Application
2	I-Application
was	O
shipped	O
to	O
Japan	O
for	O
production	O
,	O
copies	O
of	O
the	O
source	O
code	O
were	O
sent	O
on	O
separate	O
planes	O
to	O
ensure	O
that	O
the	O
game	O
would	O
arrive	O
in	O
case	O
of	O
an	O
accident	O
.	O
</s>
<s>
On	O
the	O
day	O
the	O
code	O
shipped	O
,	O
the	O
STI	O
staff	O
gathered	O
in	O
the	O
warehouse	O
and	O
celebrated	O
with	O
a	O
Sonic-themed	O
cake	O
.	O
</s>
<s>
Sega	O
aggressively	O
promoted	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
,	O
spending	O
approximately	O
$10	O
million	O
on	O
advertising	O
.	O
</s>
<s>
As	O
Sonic	B-Application
2	I-Application
was	O
Sega	O
's	O
biggest	O
game	O
of	O
1992	O
,	O
its	O
marketing	O
team	O
,	O
as	O
Game	O
Informer	O
wrote	O
,	O
sought	O
to	O
make	O
the	O
release	O
"	O
as	O
much	O
a	O
celebration	O
as	O
it	O
was	O
a	O
product	O
launch	O
"	O
.	O
</s>
<s>
Sega	O
of	O
America	O
collaborated	O
with	O
Emery	O
Worldwide	O
to	O
produce	O
stickers	O
celebrating	O
"	O
The	O
Great	O
Sonic	B-Application
2	I-Application
Shipment	O
"	O
,	O
and	O
50	O
people	O
dressed	O
as	O
Sonic	B-Application
greeted	O
the	O
three	O
planes	O
carrying	O
copies	O
of	O
Sonic	B-Application
2	I-Application
at	O
Heathrow	O
Airport	O
.	O
</s>
<s>
Sega	O
considered	O
shipping	O
the	O
cartridges	B-Protocol
with	O
holographic	B-Algorithm
labels	O
,	O
but	O
decided	O
it	O
was	O
too	O
expensive	O
.	O
</s>
<s>
Instead	O
,	O
it	O
made	O
Sonic	B-Application
2	I-Application
available	O
in	O
the	O
West	O
in	O
all	O
stores	O
on	O
the	O
same	O
day	O
.	O
</s>
<s>
The	O
North	O
American	O
and	O
European	O
release	O
date	O
,	O
Tuesday	O
,	O
November	O
24	O
,	O
1992	O
,	O
was	O
marketed	O
as	O
"	O
Sonic	B-Application
2sday	O
"	O
.	O
</s>
<s>
Initial	O
copies	O
of	O
Sonic	B-Application
2	I-Application
had	O
several	O
bugs	B-Error_Name
;	O
later	O
copies	O
used	O
a	O
patch	O
developed	O
a	O
few	O
days	O
after	O
completion	O
.	O
</s>
<s>
The	O
Western	O
cover	O
art	O
,	O
featuring	O
Robotnik	O
peering	O
over	O
a	O
gigantic	O
"	O
2	O
"	O
behind	O
Sonic	B-Application
and	O
Tails	O
,	O
was	O
illustrated	O
by	O
Greg	O
Martin	O
,	O
while	O
the	O
Japanese	O
cover	O
art	O
was	O
illustrated	O
by	O
Akira	O
Watanabe	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
broke	O
video	O
game	O
sales	O
records	O
and	O
became	O
the	O
fastest-selling	O
game	O
at	O
the	O
time	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
grossed	O
in	O
1992	O
(	O
adjusted	O
for	O
inflation	O
)	O
,	O
and	O
its	O
release-day	O
revenue	O
exceeded	O
the	O
total	O
revenue	O
that	O
the	O
bestselling	O
music	O
CD	O
of	O
1992	O
,	O
Simply	O
Red	O
's	O
Stars	O
,	O
had	O
earned	O
throughout	O
the	O
year	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
sold	O
six	O
million	O
copies	O
worldwide	O
by	O
August	O
2006	O
,	O
making	O
it	O
the	O
second-bestselling	B-Application
Genesis	I-Application
game	I-Application
behind	O
the	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
.	O
</s>
<s>
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
received	O
acclaim	O
and	O
many	O
critics	O
considered	O
it	O
better	O
than	O
the	O
first	O
Sonic	B-Application
.	O
</s>
<s>
Reviewers	O
noted	O
Sonic	B-Application
2	I-Application
was	O
similar	O
to	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
in	O
appearance	O
and	O
gameplay	O
.	O
</s>
<s>
In	O
particular	O
,	O
GamesMaster	O
felt	O
that	O
Sonic	B-Application
2	I-Application
was	O
just	O
more	O
of	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
and	O
did	O
not	O
improve	O
much	O
.	O
</s>
<s>
Critics	O
commended	O
the	O
presentation	O
,	O
with	O
EGM	O
describing	O
Sonic	B-Application
2	I-Application
as	O
an	O
impressive	O
showcase	O
of	O
the	O
Genesis	O
hardware	O
.	O
</s>
<s>
GamePro	O
,	O
Mean	O
Machines	O
Sega	O
,	O
and	O
Mega	O
wrote	O
that	O
the	O
updated	O
sprites	O
were	O
larger	O
and	O
animated	O
better	O
;	O
Mean	O
Machines	O
said	O
Sonic	B-Application
's	O
new	O
animation	O
frames	O
made	O
for	O
a	O
smoother	O
appearance	O
.	O
</s>
<s>
CVG	O
said	O
this	O
was	O
not	O
a	O
problem	O
since	O
Sonic	B-Application
graphics	O
were	O
already	O
excellent	O
.	O
</s>
<s>
Critics	O
said	O
Sonic	B-Application
2	I-Application
levels	O
were	O
larger	O
and	O
featured	O
more	O
variety	O
than	O
the	O
first	O
game	O
,	O
which	O
CVG	O
and	O
GamePro	O
wrote	O
incentivized	O
exploration	O
and	O
replayability	O
.	O
</s>
<s>
Mean	O
Machines	O
and	O
Mega	O
said	O
it	O
was	O
clear	O
that	O
Sega	O
sought	O
to	O
address	O
the	O
criticisms	O
levied	O
against	O
the	O
first	O
game	O
regarding	O
its	O
length	O
and	O
low	O
difficulty	O
,	O
though	O
Sonic	B-Application
2	I-Application
easiness	O
was	O
still	O
criticized	O
.	O
</s>
<s>
Mega	O
and	O
GamesMaster	O
wrote	O
that	O
despite	O
Sonic	B-Application
2	I-Application
larger	O
size	O
,	O
it	O
could	O
still	O
be	O
completed	O
fairly	O
quickly	O
,	O
and	O
one	O
of	O
GamesMaster	O
reviewers	O
said	O
they	O
finished	O
it	O
in	O
one	O
sitting	O
without	O
receiving	O
a	O
single	O
game	B-Application
over	I-Application
.	O
</s>
<s>
CVG	O
said	O
the	O
difficulty	O
was	O
Sonic	B-Application
2	I-Application
only	O
major	O
problem	O
,	O
but	O
GamePro	O
and	O
Mega	O
said	O
the	O
difficulty	O
was	O
remedied	O
by	O
the	O
replay	O
value	O
that	O
the	O
levels	O
 '	O
branching	O
paths	O
and	O
various	O
secrets	O
provided	O
.	O
</s>
<s>
Reviewers	O
called	O
the	O
multiplayer	O
mode	O
one	O
of	O
Sonic	B-Application
2	I-Application
best	O
additions	O
,	O
though	O
some	O
disliked	O
the	O
split-screen	O
effect	O
.	O
</s>
<s>
Mega	B-Operating_System
Drive	I-Operating_System
calling	O
him	O
cute	O
.	O
</s>
<s>
Conversely	O
,	O
GamesMaster	O
said	O
Tails	O
was	O
briefly	O
fun	O
but	O
ultimately	O
little	O
more	O
than	O
a	O
sprite-swapped	O
Sonic	B-Application
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
received	O
numerous	O
year-end	O
accolades	O
and	O
nominations	O
.	O
</s>
<s>
It	O
received	O
the	O
Golden	O
Joystick	O
Awards	O
for	O
Best	O
Original	O
Console	O
Game	O
and	O
Promotional	O
Campaign	O
of	O
the	O
Year	O
,	O
and	O
was	O
a	O
runner-up	O
for	O
the	O
Chicago	O
Tribune	O
Best	O
Game	O
of	O
the	O
Year	O
award	O
after	O
The	B-Application
Legend	I-Application
of	I-Application
Zelda	I-Application
:	I-Application
A	I-Application
Link	I-Application
to	I-Application
the	I-Application
Past	I-Application
(	O
1991	O
)	O
and	O
the	O
console	O
version	O
of	O
Street	B-Application
Fighter	I-Application
II	I-Application
(	O
1992	O
)	O
.	O
</s>
<s>
At	O
Electronic	O
Games	O
Electronic	O
Gaming	O
Awards	O
,	O
it	O
won	O
Best	O
Electronic	O
Game	O
Graphics	O
,	O
while	O
losing	O
the	O
Video	O
Game	O
of	O
the	O
Year	O
award	O
to	O
Street	B-Application
Fighter	I-Application
II	I-Application
.	O
</s>
<s>
Naka	O
refused	O
to	O
develop	O
another	O
Sonic	B-Application
game	O
if	O
he	O
had	O
to	O
work	O
with	O
the	O
Americans	O
again	O
.	O
</s>
<s>
The	O
Japanese	O
team	O
started	O
working	O
on	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
in	O
January	O
1993	O
;	O
it	O
was	O
conceived	O
as	O
an	O
isometric	B-Application
game	O
that	O
used	O
the	O
Sega	O
Virtua	O
Processor	O
chip	O
,	O
but	O
was	O
retooled	O
to	O
reuse	O
the	O
Sonic	B-Application
2	I-Application
game	O
engine	O
after	O
it	O
became	O
apparent	O
that	O
the	O
chip	O
would	O
not	O
be	O
finished	O
in	O
time	O
.	O
</s>
<s>
Many	O
of	O
Sonic	B-Application
2	I-Application
unused	O
concepts	O
were	O
incorporated	O
into	O
Sonic	B-Application
3	I-Application
and	O
the	O
next	O
game	O
,	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
,	O
including	O
the	O
Hidden	O
Palace	O
level	O
.	O
</s>
<s>
Like	O
their	O
predecessors	O
,	O
Sonic	B-Application
3	I-Application
and	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
were	O
critical	O
and	O
commercial	O
successes	O
when	O
they	O
were	O
released	O
in	O
1994	O
.	O
</s>
<s>
While	O
the	O
Japanese	O
worked	O
on	O
Sonic	B-Application
3	I-Application
,	O
the	O
American	O
team	O
developed	O
the	O
spin-off	O
Sonic	B-Application
Spinball	I-Application
(	O
1993	O
)	O
,	O
a	O
pinball	B-Application
game	O
commissioned	O
after	O
Sega	O
's	O
research	O
determined	O
that	O
Casino	B-Application
Night	I-Application
Zone	I-Application
was	O
one	O
of	O
the	O
most	O
popular	O
levels	O
in	O
Sonic	B-Application
2	I-Application
.	O
</s>
<s>
Following	O
the	O
completion	O
of	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
,	O
Yasuhara	O
quit	O
,	O
citing	O
differences	O
with	O
Naka	O
,	O
and	O
went	O
on	O
to	O
develop	O
games	O
for	O
Sega	O
of	O
America	O
.	O
</s>
<s>
Naka	O
returned	O
to	O
Japan	O
with	O
developer	O
Takashi	O
Iizuka	O
to	O
work	O
with	O
Sonic	B-Application
Team	O
,	O
and	O
was	O
reunited	O
with	O
Ohshima	O
.	O
</s>
<s>
A	O
concept	O
developed	O
during	O
Sonic	B-Application
2	I-Application
production	O
formed	O
the	O
basis	O
of	O
the	O
Sonic	B-Application
Team	O
game	O
Nights	B-Application
into	I-Application
Dreams	I-Application
,	O
released	O
for	O
the	O
Sega	B-Device
Saturn	I-Device
in	O
1996	O
.	O
</s>
<s>
The	O
American	O
team	O
developed	O
Comix	B-Application
Zone	I-Application
(	O
1995	O
)	O
,	O
The	B-Application
Ooze	I-Application
(	O
1995	O
)	O
,	O
Die	B-Application
Hard	I-Application
Arcade	I-Application
(	O
1996	O
)	O
with	O
Sega	O
AM1	O
,	O
and	O
Sonic	B-Application
X-treme	I-Application
,	O
which	O
was	O
canceled	O
in	O
1996	O
.	O
</s>
<s>
Meanwhile	O
,	O
Cerny	O
worked	O
with	O
Sony	O
Interactive	O
Entertainment	O
and	O
helped	O
create	O
the	O
PlayStation	B-Device
franchises	O
Crash	B-Application
Bandicoot	I-Application
and	O
Spyro	B-Application
the	I-Application
Dragon	I-Application
.	O
</s>
<s>
Cerny	O
and	O
Yasuhara	O
remained	O
friends	O
and	O
reunited	O
to	O
work	O
with	O
Naughty	O
Dog	O
on	O
the	O
Jak	B-Application
and	I-Application
Daxter	I-Application
series	O
in	O
the	O
2000s	O
.	O
</s>
<s>
An	O
alternate	O
version	O
of	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
was	O
developed	O
by	O
Aspect	O
Co	O
.	O
for	O
Sega	O
's	O
8-bit	O
consoles	O
,	O
the	O
Master	O
System	O
and	O
the	O
handheld	O
Game	O
Gear	O
.	O
</s>
<s>
The	O
8-bit	O
version	O
features	O
different	O
levels	O
and	O
music	O
,	O
as	O
well	O
as	O
a	O
different	O
plot	O
in	O
which	O
Sonic	B-Application
must	O
rescue	O
a	O
kidnapped	O
Tails	O
.	O
</s>
<s>
It	O
was	O
later	O
included	O
in	O
Sonic	B-Application
compilations	O
,	O
such	O
as	O
Sonic	B-Application
Adventure	O
DX	O
(	O
2003	O
)	O
for	O
the	O
GameCube	B-Application
and	O
Windows	O
and	O
Sonic	B-Application
Gems	I-Application
Collection	I-Application
(	O
2005	O
)	O
for	O
the	O
GameCube	B-Application
and	O
PlayStation	B-Device
2	I-Device
.	O
</s>
<s>
Sega	O
released	O
an	O
arcade	O
cabinet	O
version	O
of	O
Sonic	B-Application
2	I-Application
using	O
its	O
Sega	O
Mega	O
Play	O
arcade	O
system	O
board	O
in	O
1993	O
.	O
</s>
<s>
Another	O
version	O
planned	O
for	O
the	O
Genesis	O
's	O
Sega	B-Device
CD	I-Device
accessory	O
was	O
replaced	O
by	O
Sonic	B-Application
CD	I-Application
.	O
</s>
<s>
In	O
October	O
2011	O
,	O
Sega	O
released	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
1&2	O
Soundtrack	O
,	O
a	O
three-disc	O
album	O
compiling	O
music	O
from	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
and	O
Sonic	B-Application
2	I-Application
,	O
interviews	O
with	O
Naka	O
and	O
Nakamura	O
,	O
and	O
concept	O
art	O
.	O
</s>
<s>
The	O
third	O
disc	O
contains	O
"	O
Sweet	O
Sweet	O
Sweet	O
"	O
by	O
Dreams	O
Come	O
True	O
,	O
its	O
English-language	O
version	O
"	O
Sweet	O
Dream	O
"	O
,	O
and	O
remixes	O
of	O
both	O
songs	O
that	O
Akon	O
produced	O
for	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
(	O
2006	O
)	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
has	O
been	O
ported	O
to	O
multiple	O
platforms	O
.	O
</s>
<s>
A	O
Sega	B-Device
Saturn	I-Device
port	O
included	O
in	O
the	O
compilation	O
Sonic	B-Application
Jam	I-Application
(	O
1997	O
)	O
introduces	O
an	O
alternate	O
difficulty	O
mode	O
that	O
alters	O
stage	O
layouts	O
and	O
removes	O
some	O
levels	O
for	O
an	O
easier	O
experience	O
.	O
</s>
<s>
Other	O
compilations	O
featuring	O
the	O
game	O
include	O
Sonic	B-Application
Classics	O
3	O
in	O
1	O
(	O
1995	O
)	O
for	O
the	O
Genesis	O
;	O
Sonic	B-Device
Mega	I-Device
Collection	I-Device
(	O
2002	O
)	O
for	O
the	O
GameCube	B-Application
,	O
PlayStation	B-Device
2	I-Device
,	O
and	O
Xbox	B-Device
;	O
Sega	B-Operating_System
Genesis	I-Operating_System
Collection	O
(	O
2006	O
)	O
for	O
the	O
PlayStation	B-Device
2	I-Device
and	O
PlayStation	B-Operating_System
Portable	I-Operating_System
;	O
Sonic	B-Application
's	I-Application
Ultimate	I-Application
Genesis	I-Application
Collection	I-Application
(	O
2009	O
)	O
for	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
and	O
PlayStation	B-Operating_System
3	I-Operating_System
;	O
Sonic	B-Device
Classic	I-Device
Collection	I-Device
(	O
2010	O
)	O
for	O
the	O
Nintendo	B-Device
DS	I-Device
;	O
and	O
Sega	B-Operating_System
Genesis	I-Operating_System
Classics	O
(	O
2018	O
)	O
for	O
the	O
Nintendo	B-Application
Switch	I-Application
,	O
PlayStation	B-Operating_System
4	I-Operating_System
,	O
and	O
Xbox	B-Device
One	I-Device
.	O
</s>
<s>
Jam	O
,	O
Mega	O
Collection	O
,	O
and	O
Classic	O
Collection	O
include	O
Knuckles	O
in	O
Sonic	B-Application
2	I-Application
as	O
a	O
bonus	O
.	O
</s>
<s>
A	O
remake	O
of	O
Sonic	B-Application
2	I-Application
was	O
released	O
for	O
Android	B-Application
and	O
iOS	B-Application
devices	O
on	O
December	O
12	O
,	O
2013	O
,	O
and	O
for	O
Apple	B-Device
TV	I-Device
on	O
March	O
24	O
,	O
2016	O
.	O
</s>
<s>
The	O
remake	O
was	O
developed	O
by	O
Christian	O
"	O
Taxman	O
"	O
Whitehead	O
and	O
Simon	B-Application
"	I-Application
Stealth	I-Application
"	I-Application
Thomley	I-Application
using	O
the	O
Retro	B-Application
Engine	I-Application
,	O
previously	O
used	O
in	O
Whitehead	O
's	O
2011	O
Sonic	B-Application
CD	I-Application
remake	O
.	O
</s>
<s>
The	O
remake	O
adds	O
enhancements	O
such	O
as	O
widescreen	O
support	O
,	O
Knuckles	O
as	O
a	O
playable	O
character	O
,	O
time	O
and	O
boss	O
attack	O
modes	O
,	O
online	O
multiplayer	O
,	O
additional	O
multiplayer	O
stages	O
,	O
and	O
Tails	O
's	O
flying	O
and	O
swimming	O
abilities	O
from	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
.	O
</s>
<s>
Whitehead	O
redesigned	O
Hidden	O
Palace	O
with	O
input	O
from	O
Sonic	B-Application
Team	O
,	O
which	O
informed	O
him	O
that	O
STI	O
had	O
been	O
dissatisfied	O
with	O
the	O
original	O
level	O
design	O
.	O
</s>
<s>
The	O
Android	B-Application
version	O
sold	O
more	O
than	O
100,000	O
paid	O
downloads	O
on	O
the	O
Google	B-Application
Play	I-Application
Store	I-Application
by	O
2017	O
,	O
and	O
received	O
more	O
than	O
10million	O
downloads	O
by	O
2019	O
after	O
it	O
was	O
made	O
free-to-play	O
.	O
</s>
<s>
The	O
remake	O
was	O
included	O
in	O
the	O
2022	O
compilation	O
Sonic	B-Device
Origins	I-Device
for	O
the	O
Nintendo	B-Application
Switch	I-Application
,	O
PlayStation	B-Operating_System
4	I-Operating_System
,	O
PlayStation	B-Device
5	I-Device
,	O
Windows	O
,	O
Xbox	B-Device
One	I-Device
,	O
and	O
Xbox	B-Device
Series	I-Device
X/S	I-Device
.	O
</s>
<s>
A	O
Nintendo	B-Operating_System
3DS	I-Operating_System
port	O
was	O
developed	O
by	O
M2	O
and	O
released	O
as	O
part	O
of	O
Sega	O
's	O
3D	B-Device
Classics	I-Device
line	O
in	O
Japan	O
on	O
July	O
22	O
,	O
2015	O
,	O
and	O
elsewhere	O
on	O
October	O
8	O
.	O
</s>
<s>
The	O
port	O
features	O
stereoscopic	B-Algorithm
3D	I-Algorithm
visuals	O
,	O
the	O
option	O
to	O
switch	O
between	O
the	O
game	O
's	O
regional	O
variants	O
,	O
alternate	O
sound	O
and	O
visual	O
modes	O
,	O
and	O
cheats	O
.	O
</s>
<s>
M2	O
was	O
originally	O
hesitant	O
to	O
port	O
the	O
game	O
,	O
and	O
it	O
took	O
the	O
most	O
effort	O
of	O
the	O
3D	B-Device
Classics	I-Device
line	O
due	O
to	O
its	O
large	O
size	O
and	O
elaborate	O
levels	O
.	O
</s>
<s>
M2	O
also	O
developed	O
a	O
Nintendo	B-Application
Switch	I-Application
port	O
for	O
the	O
Sega	O
Ages	O
line	O
,	O
released	O
in	O
February	O
2020	O
.	O
</s>
<s>
It	O
includes	O
most	O
of	O
the	O
additions	O
from	O
the	O
3DS	B-Operating_System
version	O
,	O
as	O
well	O
as	O
the	O
option	O
to	O
use	O
Sonic	B-Application
's	O
Drop	O
Dash	O
ability	O
from	O
Sonic	B-Application
Mania	I-Application
(	O
2017	O
)	O
,	O
a	O
time	O
attack	O
mode	O
,	O
and	B-Application
Knuckles	I-Application
in	O
Sonic	B-Application
2	I-Application
.	O
</s>
<s>
Emulated	O
versions	O
of	O
Sonic	B-Application
2	I-Application
have	O
been	O
released	O
on	O
digital	O
distribution	O
platforms	O
.	O
</s>
<s>
It	O
was	O
released	O
on	O
the	B-Operating_System
Wii	I-Operating_System
's	O
Virtual	B-Application
Console	I-Application
on	O
June	O
11	O
,	O
2007	O
,	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
's	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
on	O
September	O
12	O
,	O
2007	O
,	O
Steam	B-Application
on	O
January	O
26	O
,	O
2011	O
,	O
the	O
PlayStation	B-Operating_System
3	I-Operating_System
's	O
PlayStation	B-Device
Network	I-Device
on	O
April	O
19	O
,	O
2011	O
,	O
and	O
for	O
Nintendo	B-Application
Switch	I-Application
Online	I-Application
's	O
"	O
Expansion	B-Device
Pack	I-Device
"	O
subscribers	O
on	O
October	O
25	O
,	O
2021	O
.	O
</s>
<s>
The	B-Operating_System
Wii	I-Operating_System
and	O
Xbox	B-Operating_System
360	I-Operating_System
versions	O
allow	O
users	O
to	O
play	O
Knuckles	O
in	O
Sonic	B-Application
2	I-Application
if	O
they	O
also	O
own	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
.	O
</s>
<s>
An	O
emulated	O
version	O
for	O
iOS	B-Application
was	O
released	O
in	O
April	O
2010	O
,	O
but	O
was	O
replaced	O
by	O
the	O
remake	O
in	O
2013	O
;	O
those	O
who	O
purchased	O
the	O
original	O
version	O
were	O
offered	O
the	O
remake	O
for	O
free	O
.	O
</s>
<s>
The	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
,	O
PlayStation	B-Device
Network	I-Device
,	O
and	O
Steam	B-Application
versions	O
were	O
delisted	O
in	O
2022	O
ahead	O
of	O
the	O
release	O
of	O
Sonic	B-Device
Origins	I-Device
,	O
a	O
move	O
that	O
received	O
criticism	O
on	O
video	O
game	O
preservation	O
and	O
consumer	O
protection	O
grounds	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
was	O
a	O
major	O
factor	O
in	O
keeping	O
Sega	O
competitive	O
during	O
the	O
console	O
wars	O
of	O
the	O
16-bit	B-Application
era	I-Application
in	O
the	O
early	O
1990s	O
,	O
and	O
GameSpot	O
and	O
IGN	O
described	O
it	O
as	O
the	O
game	O
that	O
solidified	O
Sonic	B-Application
as	O
a	O
major	O
franchise	O
.	O
</s>
<s>
It	O
boosted	O
Genesis	O
sales	O
enough	O
to	O
nearly	O
equalize	O
Sega	O
with	O
Nintendo	O
and	O
cemented	O
Sonic	B-Application
as	O
a	O
video	O
game	O
mascot	O
on	O
par	O
with	O
Nintendo	O
's	O
Mario	B-Application
.	O
</s>
<s>
Further	O
,	O
the	O
Sonic	B-Application
2sday	O
promotion	O
has	O
been	O
credited	O
for	O
originating	O
the	O
concept	O
of	O
the	O
"	O
street	O
date	O
"	O
in	O
the	O
video	O
game	O
industry	O
,	O
in	O
which	O
games	O
are	O
made	O
available	O
worldwide	O
in	O
all	O
stores	O
on	O
the	O
same	O
day	O
.	O
</s>
<s>
The	O
practice	O
was	O
uncommon	O
before	O
Sonic	B-Application
2	I-Application
release	O
and	O
became	O
a	O
widespread	O
industry	O
trend	O
in	O
the	O
following	O
years	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
introduced	O
many	O
elements	O
that	O
defined	O
the	O
Sonic	B-Application
franchise	I-Application
.	O
</s>
<s>
Game	O
Informer	O
wrote	O
that	O
it	O
"	O
expanded	O
the	O
formula	O
in	O
myriad	O
ways	O
,	O
giving	O
Sonic	B-Application
new	O
moves	O
like	O
the	O
spin-dash	O
,	O
bigger	O
stages	O
to	O
explore	O
with	O
more	O
branching	O
paths	O
,	O
and	O
more	O
inventive	O
boss	O
battles.	O
"	O
</s>
<s>
USGamer	O
said	O
that	O
much	O
of	O
the	O
series	O
 '	O
most-loved	O
elements	O
originated	O
in	O
Sonic	B-Application
2	I-Application
with	O
the	O
introduction	O
of	O
Tails	O
,	O
Super	O
Sonic	B-Application
,	O
and	O
casino	O
levels	O
.	O
</s>
<s>
Tails	O
became	O
one	O
of	O
the	O
most	O
popular	O
Sonic	B-Application
characters	O
;	O
according	O
to	O
Nilsen	O
,	O
Sega	O
found	O
that	O
Tails	O
was	O
as	O
popular	O
as	O
Sonic	B-Application
because	O
he	O
received	O
nothing	O
but	O
praise	O
through	O
its	O
800	O
number	O
line	O
.	O
</s>
<s>
Tails	O
starred	O
in	O
two	O
spin-offs	O
,	O
Tails	B-Application
Adventure	I-Application
and	O
Tails	B-Application
 '	I-Application
Skypatrol	I-Application
,	O
for	O
the	O
Game	O
Gear	O
in	O
1995	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
continues	O
to	O
receive	O
acclaim	O
.	O
</s>
<s>
Writing	O
in	O
retrospect	O
,	O
critics	O
said	O
it	O
refined	O
Sonic	B-Application
formula	O
with	O
greater	O
level	O
diversity	O
and	O
design	O
,	O
better	O
graphics	O
,	O
and	O
quality-of-life	O
improvements.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1	O
GameSpot	O
said	O
that	O
Sonic	B-Application
2	I-Application
"	O
does	O
everything	O
a	O
sequel	O
is	O
supposed	O
to	O
do	O
.	O
</s>
<s>
IGN	O
felt	O
the	O
emulated	O
Wii	B-Operating_System
rerelease	O
was	O
easy	O
to	O
recommend	O
.	O
</s>
<s>
TeamXbox	O
,	O
Eurogamer	O
,	O
and	O
Hardcore	O
Gamer	O
said	O
the	O
level	O
design	O
,	O
music	O
,	O
and	O
fast	O
gameplay	O
still	O
hold	O
up	O
exceptionally	O
well	O
,	O
and	O
GamesRadar+	O
called	O
it	O
"	O
the	O
most	O
user-friendly	O
of	O
all	O
the	O
Sonic	B-Application
games	O
,	O
beautifully	O
presented	O
and	O
still	O
a	O
challenge	O
if	O
you	O
want	O
to	O
complete	O
it	O
properly.	O
"	O
</s>
<s>
GamesRadar+	O
said	O
that	O
the	O
game	O
"	O
could	O
be	O
criticized	O
for	O
'	O
playing	O
itself	O
during	O
sequences	O
when	O
Sonic	B-Application
careens	O
at	O
high	O
speeds	O
,	O
but	O
countered	O
that	O
it	O
still	O
felt	O
as	O
if	O
the	O
player	O
retained	O
control	O
over	O
him	O
.	O
</s>
<s>
The	O
2010	O
iOS	B-Application
and	O
DS	B-Device
versions	O
received	O
middling	O
reviews	O
,	O
with	O
criticism	O
for	O
their	O
quality	O
and	O
lack	O
of	O
multiplayer	O
,	O
but	O
the	O
2013	O
remake	O
was	O
considered	O
the	O
definitive	O
version	O
.	O
</s>
<s>
Critics	O
praised	O
the	O
3DS	B-Operating_System
version	O
for	O
its	O
implementation	O
of	O
the	O
system	O
's	O
stereoscopic	B-Algorithm
3D	I-Algorithm
and	O
the	O
added	O
bonus	O
features	O
,	O
with	O
Nintendo	O
World	O
Report	O
writing	O
that	O
the	O
addition	O
of	O
cheats	O
made	O
difficult	O
moments	O
less	O
frustrating	O
.	O
</s>
<s>
Nintendo	O
Life	O
was	O
disappointed	O
that	O
the	O
Switch	O
version	O
did	O
not	O
include	O
the	O
2013	O
remake	O
's	O
features	O
and	O
felt	O
that	O
M2	O
should	O
have	O
chosen	O
a	O
lesser-known	O
game	O
to	O
port	O
,	O
given	O
the	O
copious	O
number	O
of	O
Sonic	B-Application
2	I-Application
rereleases	O
.	O
</s>
<s>
Listing	O
the	O
game	O
at	O
number	O
71	O
in	O
its	O
Top	O
100	O
Games	O
of	O
All	O
Time	O
list	O
in	O
2001	O
,	O
Game	O
Informer	O
wrote	O
that	O
Sonic	B-Application
2	I-Application
was	O
the	O
most	O
challenging	O
and	O
polished	O
Sonic	B-Application
game	O
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
took	O
first	O
place	O
in	O
a	O
survey	O
conducted	O
by	O
Official	O
Nintendo	O
Magazine	O
to	O
determine	O
the	O
fan-favorite	O
Sonic	B-Application
game	O
in	O
2010	O
,	O
and	O
GameZone	O
named	O
it	O
the	O
second-best	O
Sonic	B-Application
game	O
(	O
behind	O
Sonic	B-Application
3	I-Application
)	O
in	O
2011	O
.	O
</s>
<s>
GamesRadar+	O
named	O
Sonic	B-Application
2	I-Application
the	O
best	O
Sonic	B-Application
game	O
and	O
the	O
second-best	O
Genesis	O
game	O
of	O
all	O
time	O
(	O
behind	O
Streets	B-Application
of	I-Application
Rage	I-Application
2	I-Application
(	O
1992	O
)	O
)	O
in	O
2017	O
.	O
</s>
<s>
In	O
November	O
2017	O
,	O
Sonic	B-Application
Team	O
head	O
Takashi	O
Iizuka	O
said	O
that	O
he	O
felt	O
Sonic	B-Application
2	I-Application
"	O
really	O
is	O
the	O
best	O
of	O
the	O
classic	O
Sonic	B-Application
series	I-Application
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
really	O
captured	O
that	O
global	O
sense	O
of	O
game	O
design	O
and	O
level	O
design.	O
"	O
</s>
<s>
For	O
Sonic	B-Application
20th	O
anniversary	O
in	O
2011	O
,	O
Sega	O
released	O
Sonic	B-Application
Generations	I-Application
,	O
which	O
features	O
reimagined	O
versions	O
of	O
stages	O
from	O
across	O
the	O
series	O
 '	O
history	O
.	O
</s>
<s>
The	O
PlayStation	B-Operating_System
3	I-Operating_System
,	O
Xbox	B-Operating_System
360	I-Operating_System
,	O
and	O
Windows	O
versions	O
contain	O
remakes	O
of	O
Sonic	B-Application
2	I-Application
Chemical	B-Application
Plant	I-Application
Zone	I-Application
and	O
Death	O
Egg	O
Robot	O
boss	O
fight	O
,	O
while	O
the	O
Nintendo	B-Operating_System
3DS	I-Operating_System
version	O
contains	O
a	O
remake	O
of	O
Casino	O
Night	O
.	O
</s>
<s>
Additionally	O
,	O
a	O
Casino	O
Night-themed	O
pinball	B-Application
minigame	O
was	O
released	O
as	O
downloadable	B-Protocol
content	I-Protocol
.	O
</s>
<s>
Sonic	B-Application
Mania	I-Application
features	O
reimagined	O
versions	O
of	O
Chemical	O
Plant	O
and	O
Oil	O
Ocean	O
,	O
while	O
Sonic	B-Application
Forces	I-Application
(	O
2017	O
)	O
features	O
a	O
reimagined	O
version	O
of	O
Chemical	O
Plant	O
.	O
</s>
<s>
Some	O
design	O
elements	O
from	O
Sonic	B-Application
2	I-Application
feature	O
in	O
Studio	O
Pierrot	O
's	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
(	O
1996	O
)	O
original	O
video	O
animation	O
.	O
</s>
<s>
The	O
feature	O
film	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
(	O
2022	O
)	O
draws	O
inspiration	O
from	O
Sonic	B-Application
2	I-Application
,	O
though	O
it	O
is	O
not	O
a	O
direct	O
adaptation	O
.	O
</s>
<s>
The	O
Death	O
Egg	O
Robot	O
and	O
Super	O
Sonic	B-Application
appear	O
in	O
the	O
film	O
,	O
while	O
one	O
of	O
its	O
posters	O
recreates	O
Martin	O
's	O
Sonic	B-Application
2	I-Application
box	O
art	O
illustration	O
.	O
</s>
<s>
In	O
the	O
years	O
since	O
Sonic	B-Application
2	I-Application
release	O
,	O
a	O
number	O
of	O
prototypes	B-Application
have	O
been	O
leaked	O
online	O
.	O
</s>
<s>
In	O
1999	O
,	O
a	O
Sonic	B-Application
fan	O
,	O
Simon	O
Wai	O
,	O
discovered	O
an	O
early	O
prototype	B-Application
containing	O
the	O
scrapped	O
Hidden	O
Palace	O
,	O
Wood	O
,	O
and	O
Genocide	B-Protocol
City	O
levels	O
on	O
a	O
Chinese	O
website	O
and	O
shared	O
it	O
with	O
the	O
Western	O
Sonic	B-Application
fandom	O
.	O
</s>
<s>
The	O
discovery	O
played	O
a	O
significant	O
role	O
in	O
the	O
development	O
of	O
a	O
video	O
game	O
research	O
scene	O
in	O
which	O
players	O
datamine	B-Application
games	O
and	O
document	O
their	O
prototypes	B-Application
to	O
understand	O
how	O
they	O
were	O
developed	O
.	O
</s>
<s>
Journalist	O
Heidi	O
Kemps	O
presented	O
the	O
prototype	B-Application
to	O
Naka	O
during	O
a	O
2005	O
GameSpy	O
interview	O
and	O
he	O
identified	O
it	O
as	O
originating	O
from	O
a	O
preview	O
cartridge	B-Protocol
that	O
had	O
been	O
stolen	O
from	O
a	O
1992	O
New	O
York	O
City	O
toy	O
show	O
.	O
</s>
<s>
A	O
Sonic	B-Application
fan	O
discovered	O
the	O
Sonic	B-Application
2	I-Application
prototype	B-Application
featured	O
on	O
Nick	O
Arcade	O
in	O
2006	O
and	O
raised	O
over	O
1,500	O
to	O
buy	O
the	O
cartridge	B-Protocol
and	O
release	O
the	O
ROM	O
image	O
online	O
.	O
</s>
<s>
The	O
Nick	O
Arcade	O
prototype	B-Application
,	O
while	O
primitive	O
and	O
unpolished	O
,	O
showed	O
fans	O
how	O
STI	O
built	O
the	O
game	O
atop	O
the	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
.	O
</s>
<s>
A	O
high-definition	O
(	O
HD	O
)	O
fangame	B-Application
remake	O
,	O
Sonic	B-Application
2	I-Application
HD	O
,	O
entered	O
development	O
for	O
Windows	O
and	O
macOS	B-Application
in	O
2008	O
.	O
</s>
<s>
The	O
project	O
was	O
canceled	O
in	O
2012	O
after	O
the	O
release	O
of	O
a	O
game	O
demo	O
that	O
Retro	O
Gamer	O
described	O
as	O
"	O
blighted	O
by	O
programming	O
incompetence	O
"	O
,	O
due	O
to	O
high	O
system	O
requirements	O
and	O
digital	O
rights	O
management	O
that	O
inadvertently	O
triggered	O
antivirus	B-Application
software	I-Application
.	O
</s>
<s>
Sonic	B-Application
2	I-Application
has	O
also	O
been	O
noted	O
for	O
its	O
active	O
modding	O
scene	O
that	O
releases	O
ROM	O
hacks	O
featuring	O
new	O
game	O
mechanics	O
and	O
playable	O
characters	O
.	O
</s>
<s>
Modders	O
decompiled	B-Application
the	O
source	O
code	O
of	O
the	O
2013	O
Sonic	O
2''	O
remake	O
in	O
2021	O
,	O
allowing	O
it	O
to	O
be	O
unofficially	O
ported	O
to	O
any	O
platform	O
.	O
</s>
