The second in the Operation Flashpoint series, the original set the standard for First Person Shoot em ups and other Soldier sims, and to this day is still the most realistic. It was developed using actual soldier based simulators the army use.
It is going to absolutey walk over COD. Free roam on actual Modelled Islands that exist in real life? Destroy a building in one mission and it wont be there in the next, or the next etc etc? Equivalent of Hardcore mode in COD, giving you no HUD, or ammo count, just you, your surroundings, a watch and a compass etc. Radar is for Pussys
Seriously guys, check it out. Im sure there will still be people saying COD is better, but trust me... it isnt