> Interesting, if confusing (and not being the author I guess you couldn't answer any questions about what's going on).

Well, in the original VN in the lonely ending Semyon meets another one of himself, known as the Pioneer, as some time passes before his identity as another Semyon is revealed. And when it is, the Pioneer tells that he is Semyon from a parallel world, he tried all the means to escape the camp and time loop, but after never succeding concluded it is just impossible. Also concluding nothing and no one here is real he did things like torturing and killing the camp's inhabitants (first hoping to extract answers from them, then possibly just for fun). A bit later Semyon meets another Pioneer who tells him not to trust the first one. Apparently he's also from another parallel world, but in a bonus story dedicated to the Pioneer it seems like the second Pioneer is actually the future version of the first Pioneer after he realized there are also real people in this multiverse (however the bonus story itself is even more confusing the the core one, so there's a chance I got it wrong). Which might lead to believe there is only one Semyon in the end and he jumps not between parallel worlds, but between cycles in the time loop. However in the true ending we also see the Pioneer, actually lots of Pioneers/Semyons who all ride the bus when Semyon finally escapes the camp. I don't remember for sure though if this scene is from the true true ending where Semyon actually returns to the real world or the other one where he escapes the camp but still lives the rest of his life in a dream world [which he probably doesn't realise is a dream] with a girl of his choosing. Also in the true true ending where he does return to the real world he then meets all the girls from the camp (which is why it's also known as a harem ending) and they tell him there were indeed many parallel camps/worlds, and in each one only one real person. Like, in Semyon's camp only he was real, but none of the girls were, in Slavya's camp she was real, but Semyon wasn't, etc. And if I remember correctly they also experienced time loops, eventually started to remember it, then somehow cooperated (either developing same jumping-between-worlds ability as Pioneer or maybe there was a slight chance after another loop for more then one real person to get into one camp/world) and managed to escape the fake world of the camp. Also, I think I've read somewhere (author's comment or someone claming to cite an author's comment) that Semyon was special in regards to how there were indeed many Semyons (coming from parallel real worlds [not to be confused with parallel camps/worlds]), while there were originally only one of each of the girls (so did only 'our' Semyon get to meet them in the real world in the end or what? No idea). As you can see, this is all really complicated and confusing.

Now, about this piece of fanfiction, here's what I think of it. There are at least two Semyons ('our' Semyon and the Pioneer), that's where the fifty-fifty comes from. And the Pioneer kept tortuting and killing them without realizing he got to the camp/world where they are real people (or maybe in this version they were all real from the start, but the Pioneer didn't realize or didn't care). The girls don't realize there are more then one Semyon though. Him not remembering the doings of his other self don't even make them think in that direction, because loosing memory with the camp/world reset is even more common that keeping it (see how they mention they only gradually began to remember something like that has already happened).

P.S. By real people I mean people from real world who also mysteriously got into that multiverse with camps as Semyon did. The non real people are all the others (and in a camp/world where there is no real Slavya for example, there would be her non real version instead), they behave naturally as if they are real pioneers in a real pioneer camp, but if you ask them where the camp is situated or what year it is, how to leave the camp or contact the outer world, they'll avoid the question (and as apparent from the Pioneer's story, they won't answer even under torture).

Hope this helps.