Why was my Steam game revoked and removed from my library?

Steam games are revoked when the publisher instructs Valve to disable a key. This usually happens because the key was originally purchased with a stolen credit card or fraudulent payment — when the fraud is detected, the payment is reversed and the publisher revokes the key. It can also happen if the original seller filed a chargeback. As the end buyer you are not at fault, but Steam cannot restore the game for third-party key purchases. Contact the seller with your order confirmation and a screenshot of the Steam notification for a replacement or refund. If the seller refuses, dispute the charge with your bank or PayPal.