<s>
Players	O
control	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
and	B-Application
Knuckles	I-Application
the	O
Echidna	O
in	O
their	O
quests	O
to	O
save	O
Angel	B-Application
Island	I-Application
;	O
Sonic	B-Application
tries	O
to	O
stop	O
Doctor	O
Robotnik	O
from	O
re-launching	O
his	O
orbital	O
weapon	O
,	O
the	O
Death	O
Egg	O
,	O
while	O
Knuckles	O
scuffles	O
with	O
Robotnik	O
's	O
minion	O
,	O
EggRobo	O
.	O
</s>
<s>
Like	O
previous	O
Sonic	B-Application
games	O
,	O
players	O
traverse	O
side-scrolling	O
levels	O
at	O
high	O
speeds	O
while	O
collecting	O
rings	O
and	O
defeating	O
enemies	O
.	O
</s>
<s>
Sega	O
Technical	O
Institute	O
developed	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
simultaneously	O
alongside	O
its	O
predecessor	O
,	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
(	O
1994	O
)	O
;	O
they	O
were	O
planned	O
as	O
a	O
single	O
game	O
until	O
time	O
constraints	O
and	O
cartridge	B-Protocol
costs	O
forced	O
the	O
developers	O
to	O
split	O
it	O
.	O
</s>
<s>
The	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
cartridge	B-Protocol
features	O
an	O
adapter	O
that	O
allows	O
players	O
to	O
connect	O
the	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
cartridge	B-Protocol
,	O
creating	O
a	O
combined	O
game	O
,	O
Sonic	B-Application
3	I-Application
&	B-Application
Knuckles	I-Application
.	O
</s>
<s>
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
(	O
1992	O
)	O
can	O
also	O
be	O
attached	O
,	O
allowing	O
players	O
to	O
control	O
Knuckles	O
in	O
Sonic	B-Application
2	I-Application
stages	O
.	O
</s>
<s>
Attaching	O
the	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
or	O
any	O
other	O
Genesis	O
game	O
released	O
prior	O
to	O
this	O
will	O
unlock	O
the	O
"	O
Blue	O
Sphere	O
"	O
minigame	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
was	O
released	O
for	O
the	O
Sega	B-Operating_System
Genesis	I-Operating_System
on	O
October	O
18	O
,	O
1994	O
.	O
</s>
<s>
It	O
received	O
positive	O
reviews	O
;	O
critics	O
were	O
impressed	O
with	O
the	O
replay	O
value	O
and	O
lock-on	O
technology	O
,	O
despite	O
its	O
similarity	O
to	O
Sonic	B-Application
3	I-Application
.	O
</s>
<s>
The	O
games	O
sold	O
a	O
combined	O
four	O
million	O
copies	O
worldwide	O
,	O
placing	O
them	O
among	O
the	O
best-selling	B-Application
Sega	I-Application
Genesis	I-Application
games	I-Application
.	O
</s>
<s>
They	O
have	O
since	O
been	O
rereleased	O
in	O
various	O
Sega	O
and	O
Sonic	B-Application
compilations	O
.	O
</s>
<s>
Since	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
and	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
3	I-Application
were	O
initially	O
developed	O
as	O
one	O
game	O
,	O
their	O
gameplay	O
is	O
similar	O
:	O
both	O
are	O
2D	O
side-scrolling	O
platformers	O
with	O
similar	O
level	O
design	O
,	O
graphics	O
,	O
and	O
game	O
mechanics	O
.	O
</s>
<s>
However	O
,	O
in	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
,	O
unlike	O
in	O
Sonic	B-Application
3	I-Application
,	O
the	O
player	O
chooses	O
either	O
Sonic	B-Application
or	O
Knuckles	O
at	O
the	O
title	O
screen	O
,	O
Miles	O
"	O
Tails	O
"	O
Prower	O
is	O
not	O
available	O
to	O
select	O
,	O
and	O
the	O
player	O
cannot	O
control	O
two	O
characters	O
together	O
.	O
</s>
<s>
Sonic	B-Application
and	I-Application
Knuckles	I-Application
traverse	O
levels	O
differently	O
;	O
Sonic	B-Application
can	O
jump	O
higher	O
and	O
has	O
access	O
to	O
unique	O
shield	O
abilities	O
,	O
whereas	O
Knuckles	O
can	O
glide	O
and	O
climb	O
most	O
walls	O
.	O
</s>
<s>
The	O
levels	O
also	O
include	O
cutscenes	O
that	O
differ	O
based	O
on	O
the	O
character	O
selected	O
,	O
as	O
Sonic	B-Application
and	I-Application
Knuckles	I-Application
are	O
opponents	O
for	O
most	O
of	O
the	O
game	O
.	O
</s>
<s>
The	O
first	O
type	O
has	O
Sonic	B-Application
or	O
Knuckles	O
orbit	O
floating	O
,	O
glowing	O
spheres	O
,	O
jetting	O
off	O
each	O
one	O
when	O
a	O
button	O
is	O
pressed	O
,	O
while	O
a	O
fence	O
of	O
light	O
approaches	O
from	O
the	O
bottom	O
and	O
will	O
remove	O
the	O
player	O
from	O
the	O
stage	O
if	O
touched	O
.	O
</s>
<s>
Completing	O
a	O
Special	O
Stage	O
earns	O
the	O
player	O
a	O
Chaos	O
Emerald	O
;	O
collecting	O
all	O
seven	O
Emeralds	O
allows	O
the	O
player	O
to	O
turn	O
into	O
Super	O
Sonic	B-Application
or	O
Super	O
Knuckles	O
,	O
more	O
powerful	O
versions	O
of	O
the	O
characters	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
features	O
"	O
lock-on	O
technology	O
"	O
that	O
allows	O
players	O
to	O
open	O
the	O
hatch	O
on	O
the	O
cartridge	B-Protocol
and	O
insert	O
a	O
second	O
cartridge	B-Protocol
.	O
</s>
<s>
When	O
Sonic	B-Application
3	I-Application
is	O
inserted	O
,	O
the	O
player	O
can	O
play	O
through	O
both	O
games	O
as	O
one	O
,	O
Sonic	B-Application
3	I-Application
&	B-Application
Knuckles	I-Application
.	O
</s>
<s>
This	O
features	O
several	O
changes	O
to	O
the	O
games	O
,	O
such	O
as	O
slightly	O
altered	O
level	O
layouts	O
,	O
the	O
ability	O
to	O
play	O
through	O
Sonic	B-Application
3	I-Application
levels	O
as	O
Knuckles	O
or	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
levels	O
as	O
Tails	O
,	O
and	O
the	O
ability	O
to	O
save	O
progress	O
in	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
levels	O
.	O
</s>
<s>
Additionally	O
,	O
combining	O
the	O
cartridges	B-Protocol
is	O
the	O
only	O
way	O
to	O
collect	O
"	O
Super	O
Emeralds	O
"	O
,	O
earned	O
by	O
accessing	O
Special	O
Stages	O
in	O
the	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
levels	O
after	O
collecting	O
all	O
seven	O
Chaos	O
Emeralds	O
from	O
Sonic	B-Application
3	I-Application
.	O
</s>
<s>
When	O
all	O
Super	O
Emeralds	O
have	O
been	O
collected	O
,	O
Sonic	B-Application
,	O
Knuckles	O
,	O
and	O
Tails	O
can	O
transform	O
into	O
Hyper	O
Sonic	B-Application
,	O
Hyper	O
Knuckles	O
,	O
and	O
Super	O
Tails	O
respectively	O
,	O
each	O
with	O
unique	O
abilities	O
.	O
</s>
<s>
Inserting	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
wherein	O
the	O
player	O
can	O
play	O
Sonic	B-Application
2	I-Application
using	O
Knuckles	O
 '	O
abilities	O
.	O
</s>
<s>
If	O
the	O
player	O
attaches	O
any	O
other	O
Genesis	O
game	O
released	O
prior	O
to	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
,	O
a	O
screen	O
with	O
Sonic	B-Application
,	O
Tails	O
,	O
Knuckles	O
,	O
and	O
Robotnik	O
stating	O
"	O
No	O
Way	O
!	O
"	O
</s>
<s>
From	O
here	O
,	O
the	O
player	O
can	O
also	O
access	O
a	O
minigame	O
based	O
on	O
Sonic	B-Application
3	I-Application
and	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
Chaos	O
Emerald	O
Special	O
Stages	O
.	O
</s>
<s>
The	O
attached	O
cartridge	B-Protocol
determines	O
the	O
Special	O
Stage	O
layout	O
.	O
</s>
<s>
If	O
the	O
player	O
attaches	O
the	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
,	O
they	O
are	O
able	O
to	O
access	O
all	O
of	O
the	O
possible	O
variations	O
of	O
the	O
special	O
stages	O
,	O
each	O
with	O
a	O
unique	O
level	O
number	O
and	O
corresponding	O
password	O
.	O
</s>
<s>
This	O
game	O
is	O
named	O
Blue	O
Sphere	O
in	O
Sonic	B-Device
Mega	I-Device
Collection	I-Device
and	O
in	O
Sonic	B-Device
Origins	I-Device
.	O
</s>
<s>
After	O
the	O
events	O
of	O
Sonic	B-Application
3	I-Application
,	O
Dr.	O
Robotnik	O
's	O
orbital	O
weapon	O
,	O
the	O
Death	O
Egg	O
,	O
crash-lands	O
on	O
Angel	B-Application
Island	I-Application
.	O
</s>
<s>
Sonic	B-Application
travels	O
to	O
Angel	B-Application
Island	I-Application
to	O
retrieve	O
the	O
Chaos	O
Emeralds	O
to	O
defeat	O
Robotnik	O
,	O
and	O
once	O
again	O
comes	O
into	O
conflict	O
with	O
Knuckles	O
,	O
who	O
believes	O
Sonic	B-Application
is	O
trying	O
to	O
steal	O
the	O
Emeralds	O
for	O
himself	O
.	O
</s>
<s>
In	O
Hidden	O
Palace	O
Zone	O
,	O
Sonic	B-Application
fights	O
and	O
defeats	O
Knuckles	O
,	O
only	O
to	O
discover	O
Robotnik	O
stealing	O
the	O
Master	O
Emerald	O
,	O
the	O
secret	O
to	O
the	O
island	O
's	O
levitation	O
powers	O
.	O
</s>
<s>
Knuckles	O
shows	O
Sonic	B-Application
a	O
portal	O
that	O
leads	O
them	O
to	O
Sky	O
Sanctuary	O
,	O
where	O
the	O
Death	O
Egg	O
is	O
relaunching	O
.	O
</s>
<s>
Sonic	B-Application
infiltrates	O
the	O
Death	O
Egg	O
and	O
defeats	O
Robotnik	O
as	O
Super	O
Sonic	B-Application
,	O
retrieving	O
the	O
Master	O
Emerald	O
and	O
returning	O
it	O
to	O
Angel	B-Application
Island	I-Application
as	O
it	O
rises	O
back	O
into	O
the	O
sky	O
.	O
</s>
<s>
In	O
Knuckles	O
 '	O
story	O
,	O
taking	O
place	O
after	O
Sonic	B-Application
's	O
,	O
Knuckles	O
is	O
attacked	O
by	O
EggRobo	O
,	O
one	O
of	O
Robotnik	O
's	O
robots	O
.	O
</s>
<s>
He	O
chases	O
him	O
to	O
the	O
damaged	O
remains	O
of	O
Sky	O
Sanctuary	O
,	O
where	O
Mecha	O
Sonic	B-Application
attacks	O
Knuckles	O
,	O
but	O
accidentally	O
destroys	O
EggRobo	O
instead	O
.	O
</s>
<s>
Mecha	O
Sonic	B-Application
uses	O
the	O
power	O
of	O
the	O
Master	O
Emerald	O
to	O
achieve	O
a	O
Super	O
form	O
similar	O
to	O
Sonic	B-Application
's	O
and	O
fights	O
Knuckles	O
until	O
the	O
latter	O
eventually	O
defeats	O
the	O
mecha	O
.	O
</s>
<s>
Sonic	B-Application
flies	O
in	O
piloting	O
the	O
biplane	O
Tornado	B-Application
,	O
and	O
takes	O
Knuckles	O
and	O
the	O
Master	O
Emerald	O
back	O
to	O
Angel	B-Application
Island	I-Application
.	O
</s>
<s>
If	O
all	O
the	O
Chaos	O
Emeralds	O
are	O
collected	O
,	O
Angel	B-Application
Island	I-Application
rises	O
upwards	O
,	O
into	O
the	O
sky	O
.	O
</s>
<s>
However	O
,	O
if	O
the	O
player	O
has	O
not	O
collected	O
all	O
the	O
Chaos	O
Emeralds	O
,	O
Angel	B-Application
Island	I-Application
plummets	O
into	O
the	O
ocean	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
was	O
developed	O
in	O
California	O
by	O
the	O
Japanese	O
members	O
of	O
Sega	O
Technical	O
Institute	O
(	O
STI	O
)	O
.	O
</s>
<s>
Sonic	B-Application
3	I-Application
and	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
were	O
originally	O
planned	O
as	O
a	O
single	O
game	O
;	O
according	O
to	O
designer	O
Takashi	O
Iizuka	O
,	O
the	O
team	O
"	O
really	O
wanted	O
to	O
hit	O
a	O
home	O
run	O
"	O
,	O
with	O
larger	O
stages	O
that	O
took	O
longer	O
to	O
develop	O
.	O
</s>
<s>
As	O
ROM	B-Protocol
cartridges	I-Protocol
were	O
too	O
small	O
to	O
contain	O
the	O
game	O
and	O
Sega	O
wanted	O
it	O
released	O
in	O
time	O
for	O
a	O
promotional	O
deal	O
with	O
McDonald	O
's	O
in	O
the	O
US	O
,	O
Sonic	B-Application
3	I-Application
was	O
split	O
in	O
two	O
,	O
with	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
as	O
the	O
second	O
part	O
.	O
</s>
<s>
According	O
to	O
Roger	O
Hector	O
,	O
vice	O
president	O
and	O
general	O
manager	O
of	O
STI	O
,	O
the	O
lock-on	O
technology	O
was	O
conceived	O
between	O
the	O
releases	O
of	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
(	O
1991	O
)	O
and	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
(	O
1992	O
)	O
.	O
</s>
<s>
The	O
team	O
knew	O
that	O
players	O
would	O
likely	O
use	O
the	O
adapter	O
to	O
insert	O
games	O
beside	O
Sonic	B-Application
3	I-Application
,	O
so	O
they	O
implemented	O
the	O
Blue	O
Sphere	O
minigame	O
for	O
most	O
games	O
.	O
</s>
<s>
They	O
made	O
Knuckles	O
playable	O
in	O
Sonic	B-Application
2	I-Application
if	O
that	O
game	O
was	O
inserted	O
because	O
the	O
team	O
found	O
his	O
play	O
style	O
suited	O
its	O
levels	O
.	O
</s>
<s>
They	O
considered	O
including	O
the	O
same	O
functionality	O
for	O
the	O
original	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
,	O
but	O
the	O
developers	O
felt	O
Knuckles	O
 '	O
abilities	O
did	O
not	O
work	O
with	O
its	O
level	O
design	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
was	O
released	O
on	O
October	O
18	O
,	O
1994	O
.	O
</s>
<s>
It	O
was	O
released	O
around	O
the	O
same	O
time	O
as	O
Nintendo	O
's	O
Donkey	B-Application
Kong	I-Application
Country	I-Application
for	O
the	O
Genesis	O
's	O
competitor	O
,	O
the	O
Super	B-Application
Nintendo	I-Application
Entertainment	I-Application
System	I-Application
.	O
</s>
<s>
Industry	O
figures	O
called	O
the	O
coinciding	O
releases	O
a	O
"	O
battle	O
"	O
as	O
both	O
advertised	O
"	O
revolutionary	O
"	O
technological	O
advances	O
:	O
lock-on	O
technology	O
for	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
and	O
3D-rendered	O
graphics	O
for	O
Donkey	O
Kong	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
was	O
backed	O
by	O
a	O
$45	O
million	O
marketing	O
campaign	O
;	O
at	O
the	O
time	O
,	O
video	O
games	O
typically	O
had	O
a	O
marketing	O
budget	O
of	O
$5	O
million	O
.	O
</s>
<s>
Blockbuster	O
Video	O
and	O
MTV	O
co-sponsored	O
a	O
tournament	O
in	O
which	O
children	O
were	O
allowed	O
to	O
play	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
has	O
been	O
released	O
as	O
part	O
of	O
numerous	O
compilations	O
of	O
Sega	O
games	O
including	O
Sonic	B-Application
Jam	I-Application
(	O
1997	O
)	O
for	O
the	O
Sega	B-Device
Saturn	I-Device
;	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
Collection	I-Application
(	O
1997	O
)	O
and	O
Sonic	B-Application
&	O
Garfield	O
Pack	O
(	O
1999	O
)	O
for	O
the	O
PC	O
,	O
Sonic	B-Device
Mega	I-Device
Collection	I-Device
(	O
2002	O
)	O
for	O
the	O
GameCube	B-Application
;	O
Sonic	B-Device
Mega	I-Device
Collection	I-Device
Plus	I-Device
(	O
2004	O
)	O
for	O
the	O
PlayStation	B-Device
2	I-Device
,	O
Xbox	B-Operating_System
,	O
and	O
PC	O
;	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
and	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
</s>
<s>
Sonic	B-Application
Jam	I-Application
,	O
in	O
addition	O
to	O
featuring	O
the	O
original	O
release	O
,	O
included	O
some	O
new	O
"	O
remix	O
"	O
options	O
to	O
modify	O
the	O
game	O
:	O
"	O
Normal	O
"	O
mode	O
alters	O
the	O
layout	O
of	O
rings	O
and	O
hazards	O
and	O
"	O
Easy	O
"	O
mode	O
removes	O
certain	O
acts	O
entirely	O
from	O
the	O
game	O
.	O
</s>
<s>
The	O
version	O
in	O
Sonic	B-Application
's	I-Application
Ultimate	I-Application
Genesis	I-Application
Collection	I-Application
does	O
not	O
retain	O
the	O
lock-on	O
feature	O
included	O
in	O
other	O
versions	O
of	O
the	O
game	O
,	O
because	O
of	O
"	O
tight	O
development	O
times	O
"	O
.	O
</s>
<s>
The	O
game	O
has	O
been	O
re-released	O
through	O
the	O
Wii	O
's	O
Virtual	B-Application
Console	I-Application
and	O
Xbox	B-Operating_System
360	I-Operating_System
's	O
Xbox	B-Device
Live	I-Device
Arcade	I-Device
.	O
</s>
<s>
For	O
example	O
,	O
if	O
one	O
downloads	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
and	O
Sonic	B-Application
2	I-Application
,	O
they	O
have	O
the	O
option	O
to	O
play	O
the	O
corresponding	O
Knuckles	O
in	O
Sonic	B-Application
2	I-Application
game	O
.	O
</s>
<s>
When	O
the	O
PC	O
version	O
was	O
released	O
via	O
the	O
Steam	B-Application
software	I-Application
,	O
the	O
games	O
were	O
released	O
together	O
as	O
Sonic	B-Application
3	I-Application
&	B-Application
Knuckles	I-Application
as	O
originally	O
intended	O
,	O
with	O
the	O
player	O
(	O
even	O
if	O
playing	O
as	O
Tails	O
)	O
simply	O
continuing	O
at	O
the	O
beginning	O
of	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
after	O
finishing	O
Sonic	B-Application
3	I-Application
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Knuckles	I-Application
is	O
included	O
in	O
the	O
retro	O
console	O
Sega	B-Operating_System
Genesis	I-Operating_System
Flashback	O
released	O
in	O
2017	O
by	O
AtGames	O
,	O
a	O
compilation	O
of	O
45	O
Genesis	O
games	O
that	O
does	O
not	O
have	O
Sonic	B-Application
3	I-Application
.	O
</s>
<s>
Sonic	B-Application
3	I-Application
&	B-Application
Knuckles	I-Application
was	O
re-released	O
for	O
the	O
first	O
time	O
since	O
2011	O
as	O
part	O
of	O
the	O
Sonic	B-Device
Origins	I-Device
compilation	O
in	O
2022	O
.	O
</s>
<s>
All	O
versions	O
of	O
the	O
games	O
included	O
in	O
Origins	O
are	O
remasters	O
running	O
on	O
the	O
Retro	B-Application
Engine	I-Application
,	O
with	O
Sonic	B-Application
1	I-Application
,	O
2	O
and	O
CD	O
being	O
new	O
ports	O
of	O
existing	O
remasters	O
.	O
</s>
<s>
This	O
version	O
of	O
the	O
title	O
was	O
developed	O
by	O
Simon	B-Application
Thomley	I-Application
of	O
Headcannon	B-Application
,	O
who	O
previously	O
worked	O
on	O
both	O
Sonic	B-Application
Mania	I-Application
and	O
the	O
other	O
titles	O
included	O
.	O
</s>
<s>
The	O
Origins	O
version	O
features	O
the	O
original	O
"	O
Blue	O
Sphere	O
"	O
minigame	O
as	O
a	O
bonus	O
mode	O
,	O
as	O
well	O
as	O
new	O
iteration	O
of	O
the	O
mode	O
called	O
"	O
New	O
Blue	O
Spheres	O
"	O
which	O
includes	O
the	O
additional	O
sphere	O
colors	O
introduced	O
in	O
Sonic	B-Application
Mania	I-Application
.	O
</s>
<s>
Sonic	B-Application
3	I-Application
and	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
sold	O
a	O
combined	O
cartridges	B-Protocol
worldwide	O
.	O
</s>
<s>
Critics	O
praised	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
,	O
despite	O
its	O
similarity	O
to	O
its	O
predecessor	O
.	O
</s>
<s>
GamePro	O
commented	O
that	O
the	O
ability	O
to	O
play	O
as	O
Knuckles	O
makes	O
it	O
essentially	O
two	O
games	O
on	O
a	O
single	O
cartridge	B-Protocol
,	O
the	O
game	O
is	O
more	O
challenging	O
than	O
Sonic	B-Application
3	I-Application
,	O
and	O
the	O
ability	O
to	O
hook	O
the	O
cartridge	B-Protocol
up	O
to	O
Sonic	B-Application
2	I-Application
and	O
3	O
makes	O
those	O
games	O
"	O
worth	O
playing	O
again	O
"	O
.	O
</s>
<s>
Next	O
Generation	O
remarked	O
,	O
"	O
Basically	O
,	O
this	O
is	O
the	O
same	O
Sonic	B-Application
game	O
that	O
Sega	O
has	O
sold	O
for	O
the	O
last	O
three	O
years	O
,	O
just	O
wrapped	O
up	O
better	O
and	O
with	O
a	O
prettier	O
ribbon.	O
"	O
</s>
<s>
Dan	O
Whitehead	O
of	O
Eurogamer	O
preferred	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
to	O
Sonic	B-Application
3	I-Application
,	O
stating	O
that	O
he	O
could	O
not	O
fully	O
appreciate	O
its	O
predecessor	O
without	O
its	O
"	O
companion	O
piece	O
"	O
.	O
</s>
<s>
Sega	O
Power	O
review	O
praised	O
the	O
game	O
's	O
harder	O
difficulty	O
in	O
comparison	O
to	O
its	O
predecessor	O
and	O
the	O
new	O
expansion	O
of	O
levels	O
,	O
admitting	O
that	O
the	O
expansion	O
would	O
not	O
have	O
been	O
possible	O
had	O
Sonic	B-Application
3	I-Application
been	O
a	O
single	O
game	O
.	O
</s>
<s>
Sega	O
Magazine	O
review	O
similarly	O
praised	O
the	O
lock-on	O
technology	O
and	O
the	O
new	O
innovation	O
the	O
unique	O
cartridge	B-Protocol
offered	O
,	O
adding	O
that	O
Sonic	B-Application
&	I-Application
Knuckles	I-Application
hidden	O
stages	O
and	O
bosses	O
would	O
strongly	O
add	O
to	O
the	O
replay	O
value	O
of	O
the	O
combined	O
game	O
.	O
</s>
<s>
Reviewing	O
the	O
Virtual	B-Application
Console	I-Application
release	O
,	O
Nintendo	O
Life	O
writer	O
James	O
Newton	O
praised	O
its	O
support	O
for	O
the	O
old	O
lock-on	O
feature	O
of	O
the	O
original	O
release	O
,	O
claiming	O
that	O
the	O
game	O
does	O
not	O
truly	O
shine	O
without	O
having	O
purchased	O
Sonic	B-Application
the	I-Application
Hedgehog	I-Application
2	I-Application
and	O
3	O
to	O
activate	O
this	O
feature	O
.	O
</s>
<s>
For	O
the	O
series	O
 '	O
twentieth	O
anniversary	O
in	O
2011	O
,	O
Sega	O
released	O
Sonic	B-Application
Generations	I-Application
,	O
a	O
game	O
that	O
remade	O
aspects	O
of	O
various	O
past	O
games	O
from	O
the	O
franchise	O
.	O
</s>
<s>
A	O
remake	O
of	O
the	O
Sky	O
Sanctuary	O
stage	O
was	O
made	O
for	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
,	O
PlayStation	B-Operating_System
3	I-Operating_System
,	O
and	O
PC	O
versions	O
of	O
the	O
game	O
,	O
while	O
the	O
Mushroom	O
Hill	O
level	O
was	O
remade	O
for	O
the	O
Nintendo	B-Operating_System
3DS	I-Operating_System
version	O
of	O
the	O
game	O
.	O
</s>
<s>
Sonic	B-Application
&	I-Application
Sega	I-Application
All-Stars	I-Application
Racing	I-Application
features	O
a	O
track	O
inspired	O
by	O
the	O
Death	O
Egg	O
as	O
downloadable	O
content	O
along	O
with	O
the	O
Metal	O
Sonic	B-Application
character	O
.	O
</s>
<s>
The	O
sequel	O
,	O
Sonic	B-Application
&	I-Application
All-Stars	I-Application
Racing	I-Application
Transformed	I-Application
,	O
featured	O
the	O
same	O
race	O
course	O
,	O
and	O
an	O
additional	O
new	O
one	O
inspired	O
by	O
the	O
Sky	O
Sanctuary	O
stage	O
.	O
</s>
<s>
Re-imagined	O
versions	O
of	O
the	O
Flying	O
Battery	O
and	O
Lava	O
Reef	O
stages	O
,	O
along	O
with	O
the	O
Blue	O
Sphere	O
bonus	O
game	O
,	O
appear	O
in	O
the	O
2017	O
game	O
Sonic	B-Application
Mania	I-Application
.	O
</s>
