Did the director lose interest?
British Horror when done well is superb. 28 Days Later, Dog Soldiers & The Descent show how its done.
Salvage is abysmal, it starts slowly, slows down for the middle section and the less said about the end the better.
I love films that do not shout plot explanations into your face, Blair Witch, Cloverfield, The Last Broadcast et al, but to give no explanation to a conceit that unexplained murders are occurring is lazy, arrogant and just poor film-making. I went back and replayed the mumbled points that could have been important but no, "experiments that went wrong, ultimate weapon" nothing that gives a platform from which we can buy into the story.
I was waiting for the reveal, the twist, something that made the amateur film I had just sat through (twice!) make sense. Hell if they had made just your basic blood and guts slasher with creative / stomach-churning scenes it would have been forgivable but a note to film-makers;
Have a point, have a story, have an opinion or if all else fails have vat of theatrical blood and an imagination.
Under no circumstances waste your time with this film.