<s>
realXtend	B-Protocol
is	O
a	O
project	O
for	O
creating	O
an	O
open-source	O
virtual	B-Application
world	I-Application
platform	O
which	O
is	O
intended	O
to	O
extend	O
the	O
capabilities	O
of	O
OpenSimulator	B-Protocol
to	O
include	O
features	O
which	O
are	O
not	O
available	O
in	O
the	O
original	O
Second	B-Application
Life	I-Application
project	O
.	O
</s>
<s>
Like	O
OpenSim	O
,	O
with	O
which	O
the	O
project	O
collaborates	O
and	O
from	O
which	O
it	O
derives	O
much	O
of	O
its	O
code	O
,	O
realXtend	B-Protocol
is	O
intended	O
to	O
allow	O
individuals	O
and	O
groups	O
to	O
set	O
up	O
and	O
browse	O
their	O
own	O
virtual	B-Application
worlds	I-Application
without	O
having	O
to	O
be	O
connected	O
to	O
much	O
larger	O
worlds	O
like	O
Second	B-Application
Life	I-Application
.	O
</s>
<s>
It	O
is	O
created	O
by	O
the	O
realXtend	B-Protocol
Association	O
,	O
which	O
was	O
founded	O
in	O
April	O
2011	O
,	O
and	O
is	O
funded	O
by	O
both	O
realXtend	B-Protocol
Foundation	O
and	O
Oulu	O
Innovation	O
of	O
Oulu	O
,	O
Finland	O
,	O
as	O
a	O
cooperation	O
by	O
three	O
Oulu	O
based	O
companies	O
Evocativi	O
,	O
LudoCraft	O
and	O
Playsign	O
.	O
</s>
<s>
Initially	O
,	O
in	O
early	O
2008	O
,	O
realXtend	B-Protocol
published	O
a	O
custom	O
viewer	O
derived	O
from	O
Linden	O
Labs	O
's	O
own	O
SL	O
viewer	O
;	O
a	O
free	O
,	O
open-source	O
client	O
(	O
or	O
viewer	O
)	O
software	O
application	O
for	O
Microsoft	B-Application
Windows	I-Application
which	O
allows	O
for	O
viewing	O
and	O
accessing	O
both	O
Second	B-Application
Life	I-Application
and	O
multiple	O
OpenSimulator-based	O
virtual	B-Application
world	I-Application
grids	O
,	O
the	O
realXtend	B-Protocol
viewer	O
is	O
licensed	O
under	O
the	O
GNU	O
GPL	O
.	O
</s>
<s>
The	O
realXtend	B-Protocol
viewer	O
uses	O
the	O
OGRE	B-Application
engine	O
,	O
and	O
it	O
provides	O
real-time	O
shadows	O
,	O
improved	O
lighting	O
simulation	O
,	O
meshes	O
and	O
realistic	O
avatars	O
.	O
</s>
<s>
The	O
official	O
Second	B-Application
Life	I-Application
physics	O
engine	O
is	O
the	O
proprietary	O
Havok	B-General_Concept
engine	I-General_Concept
.	O
</s>
<s>
Beginning	O
in	O
2009	O
,	O
the	O
project	O
began	O
to	O
work	O
on	O
a	O
newer	O
,	O
original	O
viewer	O
,	O
codenamed	O
Naali	O
,	O
which	O
is	O
licensed	O
under	O
the	O
BSD	B-Operating_System
license	I-Operating_System
and	O
coded	O
to	O
implement	O
a	O
more	O
robust	O
viewing	O
architecture	O
.	O
</s>
<s>
The	O
new	O
viewer	O
and	O
its	O
SDK	B-Application
are	O
now	O
known	O
as	O
Tundra	O
.	O
</s>
<s>
It	O
makes	O
use	O
of	O
OpenSim	O
's	O
contributions	O
policy	O
,	O
and	O
,	O
like	O
Taiga	O
,	O
is	O
relicensed	O
under	O
the	O
Apache	B-Application
License	I-Application
v2	O
.	O
</s>
