A solider once told me that boredom is one of the most mentally challenging aspects of war. Because you can go long stretches without running into anyone, let alone your enemies, the moments when you do clash are especially intense. It's like someone switching the radio dial from a low static sound to hardcore metal.

The games that try to juxtapose conflict with stretches of non-action are usually the most successful at conveying the experience of combat. The new Tomb Raider comes to mind. You can travel awhile without fighting because there's a lot to see and do in the environment. When you do encounter adversaries, they're usually in small numbers. They'll speak to each other and respond to your attacks with unique dialogue.

On the other hand, games like Call of Duty, which overwhelm the player with hundreds of enemies at all times, fail to convey the experience of war. The key is to provide contrast between action and non-action, and to provoke suspense by limiting the scope of the conflicts so they can be felt and comprehended more easily.