For the most part, Infinity Ward has the balance just right, but frustration does creep in occasionally. One level late in the game has the player protecting a computer for a set period of time, as waves of enemies try to destroy it. It's a tense scenario, as the house the computer is in has several storeys and countless entrances, but it also feels a little unstructured and messy. While you can plant claymores in advance to booby trap the house, the reality is you have to stay close to the computer, which leaves you exposed and vulnerable. And in this game, death can come very swiftly, and in a situation like this it's easy to be taken out of the game if you're dying repeatedly. Thankfully, however, the moments of true frustration are few and far between, and the checkpoints are always close together.