I bought this copy of Killing Floor from G2A since I had free money before. So I bought a region-restricted KF1 gift, restricted to RU + CIS countries. So if you don't live in any of those countries (Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, Uzbekistan), I don't think you'll be able to join. Good luck!