Now I remember.

Hands up if you’ve played the obstacle-course introduction to the original Half Life, and when you got to the room where you had to get a security guard to help you through the security doors, the first thing you did (having been presented with a weapon in a previous room, and being confronted in this room by the first non-player character who wasn’t a hologram) was to shoot the guard in the face, just to see what happened.

Thought so.