ArmA: Queen's Gambit is an expansion pack to ArmA: Combat Operations. It requires the original game to play and adds two new story-based campaigns: The Rahmadi Conflict and Royal Flush. The first features 3 large-scale missions involving SLA, US and RACS forces, while the second contains 7 missions controlling a group of mercenaries with an approach incorporating both action and stealth.
Other additions include 2 new multiplayer missions (Urban Raid - cooperative and Battle of Porto - capture and hold) and two new environments (Porto Island and United Sahrani). It incorporates the 1.08 patch for the original game, with new vehicles and weapons. There are also a few entirely new ones, such as the 6G30 grenade launcher, the DC3 plane, the HMMWV Limousine and machine gun-mounted pickups.