I have and there is a trick. It is possible to go through the levels and not get caught by the alien but you have to stay off its radar. I've gone a few levels before it got wise that I've been around a while. Because its adapting A.I, it needs to know your around first before it starts checking vents, lockers ETC. Otherwise, as long as your quiet, it mainly stays in the vents. I made to the second part of medical before I made a loud sound and it started stalking me non-stop.