I have played ArmA 2, and it is quite a good game. However, I didn't play it for too long as it wasn't totally compatible with my system, as it was designed to run on dual core, and mines was quad core. Just to run it, I had to go into the bios every time and play around with my processor settings to make them act as if dual cores. So, ArmA 2 was good, but unfortunately couldn't play too much. I'm looking forward to ArmA 3 however, it looks awesome, and will likely be more compatible (hopefully) with my system.