After payment, you instantly receive a key to activate Killing Floor at Steam game platform without regional restrictions.

Http://store.steampowered.com/app/1250/Killing_Floor/

INSTRUCTIONS FOR ACTIVATION:

1. You need to download and install Steam http://steampowered.com/download/SteamInstall.msi
2. Login to your account or register a new one.
3. Go to the "My Games" and select "Activate via Steam ...", and enter the key received after payment.
4. Once activated, the game will appear in the game list (Library) and you can download it.