Read the whole interview here.I think the most important thing in ArmA 2 is how much effort we put into the story. We re-did the story three times until it felt right to us, until it felt entertaining and exciting and deep, etcetera...
...Also, a thing relating to the story is the whole style of the game... the graphics, the selection of units, the weapons. This has all been selected to play some kind of role in the story...
....So this time we introduced a very complex simulation of suppression - which means the AI can use suppressing fire and provide cover for each other. The AI will also try to avoid being shot by suppressing fire from the other side. Players are now affected by incoming fire, so even if I'm hidden in cover, the effect of bullets coming so close to me will result in blurred in vision and shaking hands...
...Basically if you want to fight by the military text book, you can do that. You can lay smoke cover, use it to conceal your movement. When an enemy approaches you can suppress them, try to flank him. It's more strategic, more tactical, with less units but, eventually, more intense combat. In the first ArmA we needed a lot of troops to create a really hard fight, because they usually just walked into an open space, fired and died. Now they can take cover and fire from behind corners - lean, fire, lean, fire...
...We've also put a lot of effort into the civilians, how they are spawned and how they behave during Warfare mode. You can talk to them and improve their stance towards you. There are some simple mechanisms, of course, to keep them working within the game. To be honest, we had to keep our ambitions low. But you can talk to a guy in a village, find out if he likes you - and then you work out that the source of the guerrillas in the game is the fact that two hours ago you destroyed some houses, and now those guys don't like you. It's just a thing that we like to do, and that we'd like to do in the future...
Source Armaholic.com.