Yes. This concept is very old. I have first experienced it in a game called Giants: Citizen Kabuto, a game from 2000, with STILL gorgeous graphics and gameplay that rivals Global Agenda and actually is better. Btw, If you have not played it, I highly recommend, the storyline is very humorous and has superb voice acting, especially that one of the voices is Pinky, from the Pinky and the Brain cartoons. After that I saw this in numerous FPS, as scripted missions, Warcraft 3 and so on.