The game had a whole system of ranks and qualifications based off actual Army ranks and skills.
You had to do pretty comprehensive medical training before you could be a field medic, you had to qualify as a marksman to be able to use a DMR, you had to pass the SERE school before I think night time missions and NVGs could be used, had to complete parachute training before levels you’d paradrop into, etc, and these would become available as you reached a certain number of kills or successful missions or what not.
Basically, it had a persistent progression system, and it was quite in depth…
… And if you did things like tons of team killing, or killing the instructor, not only would you end up in the brig… you’d have basically all of your progress reset.
Its about as close as you can get to permadeath in a round based, pvp shooter.