Nice to have someone from HTC joining this discussion.
If the aircraft had O2 systems or not, can we at least see the O2 system modelled as a system that can be damaged?
Perhaps we could add an O2 pressure gauge? If O2 pressure is used up, or system is damaged, then pilot being above 16K altitude will gradually start blacking out? Not the fast "pilot wounded" balckout, but a sustained slowly increasing blackout that takes a couple minutes to reach complete darkness.