I'm currently digging into 'Armed Assault' by Bohemia Interactive, the makers of Operation Flashpoint. I loved Flashpoint because of it's difficulty and realism (no you vs the entire enemy army). Now, ArmA is even harder - possibilly too hard (but isn't war hard?), and it's graphics are more dated than what I'd expect from a game of that age.
However, it is really refreshing change to CoD and it's clones which are spreading like a virus. Just watching a CoD 'veteran' playing it and dying within seconds again and again warms the old heart. Oh, note that the games labeled 'Operation Flashpoint' are not like this - they are just yet another CoD clone, admittedly a little harder than most. Damm Codemasters.