* The more kills you make the better the weapons the agents will bring like shotguns and phazers.
* The more kills you make the more agents you have to fight at a time.
* Once you hit a new level search for a randomly placed healing kit somewhere in the building.
* You can jump on top of enemies from above floors that will also hit them.
* Throwing a desk does more damage than throwing a garbage can.
* If your computer is slow it will automatically reduce quality. The lowest will remove special effects.