In the first and greatest film in the Terminator series, James Cameron's The Terminator, a terrible loop is established. We have two points of time: 1984 and 2029. In the latter point, a war between machines and humans is about to end in a victory for the humans. The machines concede that they have lost the war in space, but they do not surrender. Instead, at the last minute, they add another dimension to the war: time. The machines send a cyborg Terminator T-800 Model 101 to kill the mother of John Connor, the leader of the human resistance movement. His mother, Sarah Connor (Linda Hamilton), lives in 1984. The humans see what's up and send a soldier (and friend of John's), Sergeant Kyle Reese (Michael Biehn), to protect the mother. And it is here, on this other and higher terrain of battle, the terrain of time, that the loop occurs.
Kyle has sex with Sarah in a seedy motel, and as a result becomes the father of his leader and friend in the future, John. What this means is John is not at all a normal person with normal parents. He was not born in a standard biological sequence, which is historical, which moves through time in one direction, which has a beginning and an end. John just goes around and around forever. He is like something that can self-reproduce. And indeed, incest plays an unspoken yet very loud role in the Terminator series. This sort of thing is bound to happen when you fuck with time. Not even family-friendly Back to the Future could escape the dark pull of incest.
A loop is infinite, which in part explains why the Terminator series just keeps going on and on. But there is an even more serious problem with having John Connor be the man who leads humans to the point of victory in 2029. His very presence implies that the war is always already being fought out on the terrain of time. The human successes against the machines would not be possible without the machines trying to erase the humans' leader from the past. The machines want John to be unborn, but the effort to make him unborn is precisely what brings him into existence. This presents a critical difficulty not only for the machines, but for the humans as well.
The project of the new Terminator film, Terminator Genisys—which is the fifth film in the series, as well as a kind of reboot—is to solve the terrible problem of John Connor's loopiness. At the level of plot, the film attempts to resituate the war to and confine it in the normal dimensions of space. True, humans cannot win the war without the crazy interdimensional element, but (and here's the rub) peace can only be reached in standard space-time. The solution? The humans attempt to overwhelm John's loop with even more loops. As a result, Genisys, written by Laeta Kalogridis and Patrick Lussier, is not easy to follow. The primary 1984 to 2029 loop established in Cameron's immortal original film is challenged and intersected by other and sometimes even larger loops that are trying to free the future from the curse of John's loop. Indeed, watching Genisys—which is nowhere near as good as the first two in the series but is by no means as bad as the last two—is like listening to a fugue by Bach (check out "Die Kunst der Fuge").
The film also hints that the terrain of space might actually also be in a loop, but a stable and therefore less infuriating loop: a God loop. The idea, then, is to rationalize the loops that were accidentally initiated by time machines (man) under the overarching control of the unified master loop (God). To better understand this cosmic suggestion, pay attention to the character Detective O'Brien, performed by the second best thing about the movie, J.K. Simmons.
The reprogrammed T-800 (Arnold Schwarzenegger) of Terminator 2: Judgment Day, the second film in the series and the last to be directed by Cameron, returns and has clearly aged. He is tired, his hand shakes, his machinery is wearing out, he no longer runs but walks with heavy steps. He has also learned how to smile. War on the terrain of time has made the machine more human. We also get the impression from Schwarzenegger's performance, the best thing about this reboot, that he really wants to retire but can't. He must keep on fighting and engaging with the increasing number of loops in time. In one scene, he even explains the new complexities to clueless Kyle (now played by Jai Courtney), the father of John, with an air of exasperation. His eyes, his voice, his whole manner seem to say: How long must this war between machines and humans go on? How many more times can I be burned, shot, and hit by speeding cars? Why can't anyone see that I'm an old man now?
Though an answer is never provided, the film does actually offer a practical way out of the war, but the humans reject it. Humans are sentimental animals. We do not want a future that differs too radically from the present, but always desire for things to remain exactly the way they are: lots of suburban homes, lots of shopping malls, and lots of traffic on freeways. This fixed longing for the happy days of a possibly imaginary past guarantees many unhappy consequences. But it bodes well for the continued existence of the Terminator franchise, which must be good news for someone. 
