Let me save you time: Do not Google "free Arma 2 Reinforcements CD key generator." These sites are 100% scams. They will either:
If you only have a Reinforcements key, you cannot join Chernarus servers. If you have ARMA 2 + Operation Arrowhead keys, you can join most servers. If you add the Reinforcements key, you can join servers running BAF/PMC units/weapons.
Arma 2: Reinforcements is a standalone expansion pack that combines two major DLCs: British Armed Forces and Private Military Company. Because this game was released in 2011, finding and activating a legitimate Arma 2 Reinforcements CD key today requires navigating a few modern digital storefronts and legacy activation hurdles.
If you are coming from games like Call of Duty or Battlefield , Arma 2 will be a shock to the system.
(note: this option may only appear if the game is installed). Digital Store Accounts : If purchased from the Bohemia Interactive Store , the key is listed in your account profile or "My Games" section. Activating on Steam
A good purchase if you’re a Arma 2 fan wanting the BAF/PMC DLCs. Just verify the key’s authenticity before buying.
: You can purchase directly from the developers at bistudio.com. GOG.com : Offers DRM-free versions of the Arma series. Important Notes on CD Keys
