If you find a site selling “CD keys” for this game today, it is almost certainly a grey-market or illegitimate reseller.
Thanks to the modding community, here is how to play Operation Flashpoint: Red River without any CD key: Operation Flashpoint Red River Cd Key
Note: This method is legal if you own a legitimate copy of the game (even with a lost key). It is not a crack for pirated versions. If you find a site selling “CD keys”
The availability of keys has shifted significantly since the game's launch in 2011. Key already in use: request proof of transfer/refund
Operation Flashpoint: Red River is a tactical first-person shooter developed by Codemasters and released in 2011. As a Steam-integrated title, the "CD Key" serves as the primary digital rights management (DRM) mechanism required for installation and platform binding. Due to the age of the title and the closure of certain digital storefronts, obtaining legitimate keys for new users has become a complex issue involving second-hand markets and grey-market resellers.
Unlike its predecessor (Dragon Rising), Red River relies heavily on Valve’s Steamworks API.