The Impulse Rifle kills in one shot anywhere on the body.
To get it, go to the top floor using the middle lift and
jump off the end nearest the Impulse Rifle. You should
just make it. Quickly jump off there because your enemies
can easily see you.
You can get Ballistic Armor by going to the top floor and
jumping off the edge nearest the doorway. Go through there
and the armor will be on the right-hand side. There are
extra rockets to the left.
You can win the match easily by gaining the Rocket Launcher
from the first floor. Then you can just stand on the top floor
and keep shooting at your opponents from the side nearest the
lift (not the middle one). Enemies spend most of their time there.