Now includes all three premium DLC packs (Unto the Evil, Hell Followed, and Bloodfall), maps, modes, and weapons, as well as all feature updates including Arcade Mode, Photo Mode, and the latest Update 6.66, which brings further multiplayer improvements as well as revamps multiplayer progression.
Activating the steam key
1) You must download and install Steam http://steampowered.com/download/SteamInstall.msi (if not already installed).
2) Create a new account on Steam or go to an existing one.
3) Select "Activate via Steam ..." in the "My Games" section, and enter the key received after payment.
4) After activation, the game will appear in your list of games and you can install it.
Please leave feedback after successful activation of the game.