So, Sam is essentially all alone up there, but he only has two weeks to go before he can make the long-awaited journey home. Then he finds out he's not as alone as he thought. Another Sam turns up, also played by Rockwell, and after getting over their initial shock, the pair begin circling each other suspiciously. Each Sam accuses the other of being a clone, and then the realisation starts to dawn: what if they're both clones? Where is the real Sam? And are there more Sams stashed away somewhere? The editing, cinematography and visual effects trickery utilised to create the illusion of the two Sams interacting with each other is hugely impressive, but Rockwell is the man who really sells it.
Like Jeremy Irons in Dead Ringers, Rockwell successfully delineates between two distinct characterisations, and manages to create a dynamic and tension between them. Sam One is likably bedraggled, having settled into the monotony of his job and biding his time until it's time to go home, while Sam Two is a little prickly and hostile – a replica, one presumes, of the Sam that initially accepted this position. As Sam One begins to degenerate, Sam Two gradually starts to come to terms with his situation, thus becoming more sympathetic, and Rockwell charts the development of both versions with remarkable skill. He's the only special effect the film needs.
After all, a film like Moon doesn't exactly have a lot of room in the budget for the kind of CGI-led spectacle one expects to find in a summer science-fiction thriller. The film cost something in the region of $5 million to produce, and the filmmakers have managed to squeeze every drop of value out of that tiny amount. Most of the film takes places with the confines of the Lunar Industries base (there's a nice irony in the fact that the dastardly corporation behind Sam's trauma is mining clean renewable energy), and many of the exterior shots are filmed with the use of miniatures, which adds a pleasing physicality to the surrounding moonscape.
The interior design of the base itself has a distinctly 70's vibe, which is probably intentional on the part of Jones, who references classic sci-fi films throughout – a hint of Solaris here, a dash of Silent Running there – but he also manages to develop his film's own individual personality. The fluid camerawork from Gary Shaw and Clint Mansell's haunting, instantly memorable score are huge factors in this regard. Most importantly, Moon is built upon a solid screenplay, with a story that makes sense and is as entertaining as it is intellectually stimulating. Jones has plenty of ideas to go along with his confident direction, and Moon's narrative subverts our expectations in a number of ways, although one could argue that the film is so thematically rich it has a tendency to touch on ideas rather than fully develop them. There's also a slight lull in the action around halfway through the picture, just after the two Sams have established exactly what's happening to them, but this is a minor flaw in a film that is generally well-paced, and which builds to a satisfying climax.
Ultimately, Moon succeeds because it is what so many bigger-budget films in this genre forget to be, a very human story, with Sam's experience touching on our fear of loneliness and death in a moving fashion. It all goes to show that you don't need a huge budget to make a first-rate science-fiction film; certainly not when you have buckets of ingenuity, a surfeit of ideas, and a central performance that ranks high among the year's best.