This is the very first sub 3 in the alien isolation main campaign. Also a world record. Hoollllyyy shiiiit. So: I had really good times on many levels, but this is still beatable. There IS a dialogue glitch in M15, which saved 40 seconds, but I also lost significant amounts of time due to being AFK too long twice, a bad M6, and a stupid facehugger death in M18. Far from perfect, plenty improvable. But still a really good run.
*Time includes loads.