"<Movement Check, Over.>"
This reminded me of that moment in... was it Black Mesa Blue Shift? Black Mesa? I don't remember but that moment where someone opens a door for you, tell you something and then a Grunt they thought was dead gets up, the door closes and you hear the Grunt killing them... boi. Amazing piece!
Wait I rewatched, it's a guard and a Grunt spawns behind him and beats him to death behind the door.
check. your. zone.