<s>
Time-Gate	B-Application
(	O
also	O
known	O
as	O
Timegate	O
,	O
4D	O
Time-Gate	B-Application
or	O
4D	O
Defender	O
)	O
is	O
a	O
ZX	B-Operating_System
Spectrum	I-Operating_System
game	O
from	O
Quicksilva	O
,	O
and	O
one	O
of	O
the	O
first	O
3D	O
combat	O
games	O
.	O
</s>
<s>
Time-Gate	B-Application
had	O
one	O
embarking	O
on	O
a	O
perilous	O
mission	O
to	O
repel	O
the	O
Squarm	O
invaders	O
who	O
have	O
conquered	O
Earth	O
,	O
by	O
fighting	O
through	O
hordes	O
of	O
same	O
,	O
thus	O
finding	O
and	O
locating	O
the	O
time-gates	B-Application
(	O
hence	O
the	O
name	O
)	O
and	O
using	O
the	O
gates	O
to	O
travel	O
back	O
through	O
time	O
to	O
an	O
earlier	O
era	O
,	O
where	O
one	O
fought	O
through	O
more	O
Squarm	O
to	O
find	O
another	O
gate	O
.	O
</s>
<s>
Time-Gate	B-Application
,	O
due	O
to	O
its	O
intense	O
use	O
of	O
machine-code-driven	O
sound	O
,	O
placed	O
more	O
stress	O
on	O
the	O
Spectrum	O
's	O
sound	O
capabilities	O
than	O
previous	O
games	O
,	O
and	O
thereby	O
inadvertently	O
revealed	O
a	O
design	O
flaw	O
in	O
early	O
machines	O
,	O
whereby	O
the	O
Time-Gate	B-Application
sound	O
effects	O
would	O
crash	O
those	O
machines	O
.	O
</s>
