I had ArmA II on my sight for a while now. However, it looks like its expansion, "Operation Arrowhead", is a standalone game. Does it means that it includes content from the original game? If so, is there a point in buying "Combined Operations", the package that includes both games, or will Operation Arrowhead be enough?
Being a standalone means that you don't need the original game to play it, not that it includes the base game contents. So, if you want to get the full experience you should get the Combined Operations pack.
Also, both games in the pack are required if you want to play the popular mod DayZ