ARMA 2 or ARMA 2: Operation Arrowhead for Multiplayer?

Arma II is a first- and third-person tactical shooter that simulates a military operation in the midst of a growing civil war in the fictitious European country of Chernarus. The sequel to Armed Assault and the spiritual heir to Operation Flashpoint, Arma II sets a new standard for realistic military simulation games. While Bohemia Interactive's games have always been detailed and ambitious,