<s>
Zero-K	B-Application
is	O
a	O
free	B-Application
multi-platform	B-Operating_System
open	B-Application
source	I-Application
real-time	O
strategy	O
video	O
game	O
.	O
</s>
<s>
Initially	O
based	O
on	O
content	O
from	O
Total	B-Application
Annihilation	I-Application
on	O
the	O
open	B-Application
source	I-Application
Spring	B-Application
Engine	I-Application
,	O
it	O
was	O
forked	O
and	O
all	O
proprietary	O
content	O
replaced	O
,	O
and	O
evolved	O
into	O
a	O
completely	O
new	O
game	O
with	O
unique	O
features	O
.	O
</s>
<s>
Among	O
the	O
games	O
powered	O
by	O
the	O
Spring	B-Application
Engine	I-Application
,	O
Zero-K	B-Application
makes	O
extensive	O
use	O
of	O
Lua	B-Language
scripting	I-Language
for	O
interface	O
and	O
gameplay	O
changes/enhancements	O
,	O
as	O
well	O
as	O
unique	O
real-time	O
strategy	O
concepts	O
such	O
as	O
a	O
flat	O
technology	O
tree	O
.	O
</s>
<s>
Zero-K	B-Application
has	O
similar	O
gameplay	O
to	O
Total	B-Application
Annihilation	I-Application
.	O
</s>
<s>
The	O
economy	O
in	O
Zero-K	B-Application
,	O
consists	O
of	O
two	O
resources	O
,	O
Metal	O
and	O
Energy	O
which	O
are	O
used	O
to	O
create	O
and	O
repair	O
buildings	O
and	O
units	O
.	O
</s>
<s>
The	O
interface	O
allows	O
players	O
to	O
build	O
up	O
large	O
armies	O
and	O
bases	O
with	O
ease	O
so	O
the	O
player	O
is	O
free	B-Application
to	O
concentrate	O
on	O
actual	O
tactics	O
and	O
strategy	O
.	O
</s>
<s>
Zero-K	B-Application
is	O
almost	O
unique	O
in	O
having	O
this	O
level	O
of	O
control	O
.	O
</s>
<s>
Zero-K	B-Application
can	O
be	O
played	O
online	O
in	O
1v1	O
,	O
team	O
,	O
or	O
free	B-Application
for	O
all	O
(	O
FFA	O
)	O
style	O
battles	O
,	O
as	O
well	O
as	O
playing	O
cooperatively	O
against	O
Chickens	O
,	O
bots	O
or	O
in	O
the	O
campaign	O
.	O
</s>
<s>
Planet	O
Wars	O
is	O
an	O
massively	O
multiplayer	O
online	O
style	O
strategy	O
game	O
tied	O
to	O
Zero-K	B-Application
where	O
individual	O
battles	O
are	O
fought	O
against	O
other	O
players	O
to	O
gain	O
"	O
influence	O
"	O
on	O
planets	O
.	O
</s>
<s>
Zero-K	B-Application
includes	O
a	O
unique	O
game	O
mode	O
called	O
Chickens	O
.	O
</s>
<s>
Chicken	O
games	O
are	O
essentially	O
similar	O
to	O
tower	B-Application
defense	I-Application
games	I-Application
,	O
except	O
the	O
player	O
is	O
free	B-Application
to	O
build	O
any	O
units	O
.	O
</s>
<s>
Zero-K	B-Application
is	O
released	O
under	O
"	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
or	O
Public	O
Domain	O
unless	O
otherwise	O
specified	O
"	O
.	O
</s>
<s>
Zero-K	B-Application
was	O
released	O
on	O
Steam	B-Application
on	O
27	O
April	O
2018	O
.	O
</s>
<s>
PC	O
Gamer	O
named	O
it	O
2017	O
"	O
One	O
of	O
PC	O
Gamers	O
best	O
free	B-Application
games	O
of	O
2017	O
"	O
.	O
</s>
