From the reviews it is clear that a lot of people did not understand the movie. I write this in an attempt to explain it to those who already saw the movie. John (Scott Adkins) seems to wake up from a coma, after 9 months - or so he is told - still freshly remembering how a guy named Deveraux (Jean-Claude Van Damme) brutally killed his family. The truth however is that this John is a new clone, with implanted memories of a non-existent family. Obviously, also the killing did never happen. An FBI agent (Rus Blackwell) has some "questions" for John as soon as he wakes up, showing him a photo of the killer and providing John with a name. The objective of this all is to make John think he has free will and make him want to hunt down and kill Deveraux. Deveraux is wanted badly by the government because he's running an underground organisation that frees clones like John from the government and gives them the truth and gives them back their free will by removing any false memories they might have. When John goes out exploring he meets people that he never saw before (obviously, he was just born) but who seem to recognize him. At this point we don't know much of the background story yet, so it's a real mystery when we learn on a few occasions that John apparently can be very violent. First we hear from his ex-girl friend that he once beat a man half-to-death in front of the club where she works (which is why he isn't welcome anymore there), then we meet a guy in some storage building who looks awfully deformed with scares, which apparently is the work of John and reveals that John killed a good friend of himself! At last John finds his former clone, and things become more clear: the previous John had been sent on the same mission - albeit without the false memories about having a family. This John has been freed by Deveraux and worked for him for a while, until he felt he was now the slave of Deveraux instead of the government and left him. Meanwhile Deveraux and his recruits are also hunting John, thinking he is the traitor who left them. After our John kills Magnus, the guy that is hunting him (Andrei Arlovski), finds the first John and kills him (because he attacked the girl, not sure why myself), things change. He lets himself get captured by Deveraux's men and is finally revealed the real truth. They offer him to remove his false memories which at first he agrees to. However, when he is at the verge of losing the memories of his wife and daughter, he freaks out and goes on a killing spree instead, holding on to his memories as real. So, in the end, the government seems to succeed in their plan that making it a personal matter for their clone was the key to get through to Deveraux. What they did not foresee however is that John also holds the government responsible for his pain, whether or not Deveraux killed his family or not: if he did then the government set him up to it in order to make him want to kill Deveraux. It's the same to John. After Deveraux let himself be killed, John is now the respected leader of the other universal soldiers. The story gets in a stream acceleration in the end, because apparently they went and got the last container that had to be sent "upstream" which contained the last equipment needed to clone people. When John meets with the FBI agent again he is not alone. The agent boosts about his achievement (by giving John false memories) but John kills him... and replaces the agent with a clone. From there we can guess what kind of fight is going to follow, but I suppose that will indeed be part of a future movie.
Output: Question: who killed a good friend of himself?, Answer: John