<s>
Nuclear	B-Application
Dawn	I-Application
is	O
a	O
post-apocalyptic	O
first-person	O
shooter	O
real-time	O
strategy	O
hybrid	O
video	O
game	O
.	O
</s>
<s>
It	O
was	O
originally	O
announced	O
in	O
February	O
2006	O
as	O
an	O
amateur	O
mod	O
for	O
the	O
Source	B-Application
engine	I-Application
,	O
but	O
in	O
April	O
2009	O
was	O
revealed	O
to	O
have	O
become	O
a	O
commercial	O
project	O
,	O
still	O
using	O
Source	B-Application
,	O
aimed	O
at	O
Windows	B-Application
PCs	I-Application
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
</s>
<s>
Nuclear	B-Application
Dawn	I-Application
suffered	O
a	O
protracted	O
development	O
cycle	O
as	O
a	O
mod	O
,	O
leading	O
to	O
criticism	O
that	O
it	O
was	O
vaporware	B-Application
.	O
</s>
