my favourite is the operation flash point gold edition came out in 2003. I am still [playing it with net working. Best about this game is you can create your own army groups..up to 200 man or more -untill cpu crash. I playe dwith friends and we both have 120 men on each side. Who ever gets the highest kill or survied is the winner.
The mission editing program is part of the game, you are able to create your army groups over a size of 100kmX100km maps. thats huge..so far with the new games, I have not found one can match this freedomness.

These days, with cpu 5600. its a beatuty for this massive battle field effects, imagine you have 120 plus men running up the beach beside you attcking enemies on the other side-upper hill. Its awesome