Chainsaw

The Chainsaw is a new close combat weapon introduced in Left 4 Dead 2. As seen in the beta version footage, using this weapon against the Infected can bring them the worst injuries, sometimes cutting them in half.

It is stored in the same slot as the pistol, making yet another tactical choice in the game. It has limited uses, meaning that the player must use it wisely, as they will eventually run out of gas and will leave the player with only their primary weapon. Like the other close combat weapons, it can kill every Common Infected in one hit, but it has its disadvantages, as the Survivors cannot use any other weapons while carrying a close combat weapon. This makes it extremely dangerous to attempt combat with Special Infected, as it will take couple of seconds to drop the weapon and assist a pinned Survivor.

The chainsaw is not really meant to be used against Special Infected; using it on a Boomer would spread bile over the Survivors, and using it against a Spitter would leave you right in the middle of the goo. Against a Witch or Tank, it would do little to no damage.

Trivia

 * The chainsaw was one of the first close combat weapons to be revealed and one of the last to be shown in a gameplay video.
 * When used, the base of the chainsaw seems to be red, differing from the picture, showing it being yellow (although the red color could also be splattered blood).
 * The chainsaw is the only close combat weapon that has limited uses..