In 1984, The Terminator took what could've been a B-movie situation, and made it legit
This probably doesn't surprise anyone, but a director like James Cameron has always had big ideas. So, starting his career directing films like Piranha 2: The Spawning, in a genre that could only realistically hold a talent of his attributes for so long was always going to be the situation. Cameron's second film, The Terminator proved to not only be a testing ground for his own nascent methods as a young filmmaker, but introduced some "B-Movie" methodology into the Megaplexes of the 1980's.
For those uninformed, the plot is as follows: the Terminator (Arnold Schwarzenegger), is a cyborg sent from the future, where machines and a human resistance wage a seemingly never ending war against each other for world domination. It has been sent back in time to terminate the mother (Linda Hamilton) of the man who leads the human resistance, ensuring he'd never be born in the first place. To stop all of this, the resistance also sends their own soldier, Reese (Micheal Biehn) back in time. Only, he's less a cyborg, and more a... dude. Thus, the battle of man against machine plays out in the present in order to save the future. ...or something like that.
So, there's the basic plot. Very sci-fi. Very B-movie. And there's nothing wrong with that on its face! However, that's not always going to play to wide audiences, necessarily. The Terminator, though, rises above any inclinations you have to write it off time and time again. This is generally done in the way that Cameron puts his stamp on the film in intriguing ways.
For one, it's in the contrast of the film's set pieces. Starting so loud and piercing at the film's open with all of those impressive moving parts on the battlefield. Looking back now, and taking into account the constraints of the time period, the lack of CGI is even more of a marvel, considering the action it is able to pull off in just the introduction alone. Then, moving over to the silence, and more subdued arrival of our villain in the present day, establishing all of his vicious dominance. Not so much with the noise of the explosions, but the bright red blood across a canvas, now to be filled. It's a balance that is established between chaos and the quiet, which is an element that is returned to throughout the film.
Cameron also has no shame for working under Director John Carpenter at the start of his career, and his horror influenced choices are also on display spanning various key moments throughout The Terminator. For instance, a particularly suspenseful scene where our three principal characters meet for the first time in the midst of a God damned shoot out. The shoot-out itself is actually kind of over the top, in a way; but the scene is all the better for it. All done in an 80's club....in friggin' slow-motion. There's that particular type of 80's dancing all around, likewise, in slow-motion. The scene is backlit by this beautifully refracted neon, and this handsomely shot cinematography. Finally, it utilizes this wonderful, propulsive, synthesized score that may as well have been composed by Carpenter himself. It's honestly just fantastic.
I suppose my point is that, there's a careful composition here that shows a strong, steady hand. While it may not provide an utter "masterpiece" at the end of the day, the devil was always going to be in the details. Choosing Schwarzenegger as his terminator, for instance, was a very interesting choice. It was off the heels of Conan the Barbarian, and this is a role that, not only finds him as the villain, but ultimately only has 18 lines of dialogue. Again, all of this adds up to The Terminator rising above its confines, and succeeding in spite of them. Time-traveling cyborg with an inexplicable Austrian accent? Honestly, who cares? This shit rules.
Given The Terminator's success, it's really not a surprise how massive the film's sequel, T2: Judgement Day turned out to be. Really, though, the two films are just on different planets. It's not, however, that they have completely different aims. It's where they were able to start from, which was such a key part of the story for Cameron. The second is an epic odyssey of hope, bent on saving the world from its destruction; the first ends while ominously starting it. Maybe one didn't need the other? Not necessarily true. Not necessarily false? If you step back even farther still, (God forbid) what you find is a monster of a legacy, stitched together by the sheer will, creativity and the literal nightmares of its creator. That kind of sounds like the plot of an old fashioned B-movie in and of itself.