The screensaver can activate while the game is running. This is not standard behavior when it comes to most PC games, and I feel it should be changed.

One reason I feel it should be changed is that there will be certain situations (such as lying in wait for an ambush) where you are not active for extended periods of time, and a screensaver switching on can result in some pretty bad performance issues or negative experiences within the game (say you click to get rid of the screensaver, and it shoots your buddy in the face).