Left4Dead on L4D2

image is link to blog

The first game add-on for Left 4 Dead 2 brings the original Left 4 Dead (L4D1) Survivors down south for a meeting with the L4D2 cast, while delivering new single-player, multiplayer and co-operative gameplay for the PC and Xbox 360.

The Passing also introduces a series of weekly game mode events dubbed "Mutations." These week-long runs of new gameplay modes range from "Realism Versus" mode to "Chainsaw Massacre," which gives all players chainsaws with an unlimited supply of gasoline. There are over 20 Mutations planned, each playable on all L4D2 Campaigns. Mutations are exclusively available to owners of "The Passing" DLC.

In addition, "The Passing" offers a new co-operative challenge mode of play, support for infected bot play in Versus, a new "uncommon common" zombie class (the fallen survivor), melee weapon (golf club), and firearm (M-60).