This is a fun one, the intensity ratchets up really fast, not a lot of games can create such a tense atmosphere this effectively. The Wilhelm scream is the icing on the cake, even if I have to lose a precious soldier to hear it. All of the sound effects are very visceral and contribute a great deal towards the sense of dread in the game, and that makes it so that when you pull off an effective strategy it's very satisfying, since you really feel like you're fighting for the lives of your soldiers.