<s>
Sever	O
is	O
a	O
first-person	O
shooter	O
video	O
game	O
for	O
the	O
Game	B-Device
Boy	I-Device
Advance	I-Device
handheld	B-Application
game	I-Application
console	I-Application
.	O
</s>
<s>
The	O
gameplay	O
is	O
similar	O
to	O
other	O
early	O
FPS	O
titles	O
such	O
as	O
Doom	B-Application
,	O
in	O
that	O
all	O
of	O
the	O
graphics	O
for	O
enemies	O
and	O
weapons	O
are	O
2D	O
sprites	O
in	O
a	O
3D	O
setting	O
,	O
and	O
the	O
controls	O
utilize	O
the	O
d-pad	B-Device
for	O
tank-like	O
movement	O
and	O
shoulder	O
buttons	O
for	O
strafing	O
.	O
</s>
<s>
Sever	O
utilizes	O
an	O
in-house	O
graphics	O
engine	O
,	O
first	O
showcased	O
by	O
Crawfish	O
with	O
the	O
opening	O
level	O
of	O
Doom	B-Application
II	I-Application
,	O
leading	O
up	O
to	O
the	O
launch	O
of	O
the	O
GBA	B-Device
.	O
</s>
<s>
Mawson	O
admitted	O
that	O
building	O
a	O
proprietary	O
,	O
first-person	O
engine	O
for	O
the	O
GBA	B-Device
was	O
very	O
difficult	O
,	O
requiring	O
much	O
trial	O
and	O
error	O
.	O
</s>
<s>
Crawfish	O
's	O
3D	O
raycasting	B-Algorithm
engine	O
for	O
Ecks	O
vs	O
.	O
</s>
<s>
Sever	O
was	O
originally	O
written	O
in	O
C	B-Language
,	O
but	O
was	O
later	O
optimized	O
into	O
machine	B-Language
code	I-Language
for	O
higher	O
processing	O
speeds	O
.	O
</s>
<s>
European	O
developmental	O
director	O
Joe	O
Booth	O
felt	O
that	O
although	O
the	O
game	O
's	O
engine	O
was	O
meant	O
to	O
"	O
push	O
the	O
GBA	B-Device
envelope	O
"	O
of	O
environment	O
interaction	O
and	O
background	O
animation	O
,	O
its	O
multiple	O
game	O
modes	O
set	O
it	O
apart	O
from	O
other	O
FPSs	O
on	O
the	O
handheld	B-Application
.	O
</s>
<s>
A	O
PlayStation	B-Device
2	I-Device
version	O
of	O
Ecks	O
vs	O
.	O
</s>
<s>
IGN	O
gave	O
the	O
game	O
an	O
"	O
outstanding	O
"	O
9.0/10	O
and	O
an	O
Editor	O
's	O
Choice	O
award	O
,	O
calling	O
it	O
"	O
the	O
best	O
GBA	B-Device
first	O
person	O
shooter	O
to	O
date	O
"	O
and	O
"	O
one	O
of	O
the	O
best	O
four	O
player	O
games	O
made	O
yet	O
for	O
the	O
Game	O
Boy	O
Advance.	O
"	O
</s>
