Never played it. This is the first cod game Ive bothered buying for online play!
I would have played UO for its single player though, but never got round to it!
Anyways, dont ever say ArmA isnt realistic just because it has crosshairs.
The game simulates so much stuff, its unimaginable. And to compare it to CoD4 is close to blashphemy.
Where are bullet ricochets in CoD4? Where is bulletdrop in CoD4? Does firing your weapon make your vision go dark in nightvision goggles in CoD4? (remember, your eyes need adjusting to the device, and to light sources. ArmA models this, even with flashes from your rifle)
There are so many examples of ArmA simulating things or keeping other stuff in check, like belltowers going on on exactly the hour, or half an hour.
There's a 1 on 1 scale day and night cycle, so if you put the game on the same timezone as you have while its still light, and it goes dark outside, so will ArmA at the same time.