I've always adored the audio design of the Half-Life series and especially the really creepy way that the Combine soldiers speak. This video just gives you the radio chatter of Freeman storming the beach with his Antlion soldiers and even intersperses the randomly-generated dialogue to simulate their Combine teams being taken out by him one after another.
There's so much characterization built into this shit, too. You can hear the soldiers panicking as they get overrun and calling for help.
In this other one you can hear the Overwatch as well, and at one point the commander incredulously reports that Freeman is controlling antlions https://youtube.com/watch?v=YJZiIjyeT78&feature=shares
also the way the combine soldier voice gets corrupted when they're turned into zombines used to scare the hell out of me as a kid