Great price for an awesome game.
From the Developers Website:
-ArmA II models real world ballistics & round deflection, materials penetration, a realtime day/night cycle and dynamic wind, weather and environmental effects.
-A player-driven story
-Explore multiple paths through a branching campaign. Your actions have consequences!
-Seemlessly blends FPS, RTS and RPG elements
-Fight first-hand or control multiple squads. Manage resources and watch your units develop.
-Dynamic conversation system
-Talk to teammates, allies and civilians. Win hearts and minds.
No scripts, no pre defined pathways. AI adapt and use the open environment on the fly.
-60 weapons, 120 air, land and sea vehicles
A comprehensive collection of modern military materiel!
-The most rewarding multiplayer environment
-Fully cooperative campaign, massive PvP battles over air, land and sea. Fight friends online for control of 225sq kilometers of real-world terrain!
-Intuituive, powerful mission editor
Design your own mission in minutes or create intricate and unique campaigns.
"A brilliantly in-depth and vast war simulator that rewards your patience... If ArmA 2 hooks you in, you've just found a war game capable of providing infinite entertainment, and that's astonishing."
PC Gamer UK - GAME OF THE YEAR 2009 - THE MOST PC GAME
Combined operations is also on offer for £14.99 http://www.gamersgate.co.uk/DDB-A2COEU/arma-2-combined-operations-bundle
1st deal so please be gentle :)