It’s a tough slog, inventing new ways to tell time travel stories. The more clock rewinding/propelling movies we see, the less capacity they have to surprise us. Thus the desire for filmmakers to get loopier and wilder when they shake around the hour glass.

Last year’s SCI-FI who/when-dun-it Source Code followed a modern punch-happy Poirot who could time travel but for only eight minutes a pop, and always onto a train — a sort of Groundhog Day on the Orient Express — before being spat out into a horrifying reality where he discovers his brain is wired into a futuristic air conditioner.

The Butterfly Effect (2004) transported Ashton Kutcher across moldable versions of the space/time continuum, with horrifying rape dungeon repercussions, simply by having him read a child’s diary.

Hot Tub Time Machine (2010) features a particularly comfortable mode of transport, though the price for commuters is having to tolerate John Cusack on magic mushrooms, Crispin Glover minus an arm and Chevy “can’t be bothered with this acting jazz anymore” Chase.

There are others, many others. In fact there are too many weird twists on the time travel pic to name — and it’s not exclusively a recent phenomenon. Fish out of water romp Time After Time (1979) captured H.G Wells flying off to the future to track down Jack the Ripper after crazy ol’ Jack stole his ride and found himself in paradise, slashing up a storm in a world of soap operas, sharp knives and skimpy clothing.

Concepts explored by directors who dabble in time travel yarns often concern the “what if I see/kill/high five myself in the future/past” and the exploration of chase-your-trail conundrums. What would happen, for example, if you visited the past and killed your father or mother, thus eradicating yourself from existence? If travel travel machines end up costing serious dosh, and it’s hard to imagine they wouldn’t, lest any Johnny-cum-lately fling themselves back in time to bet big on that sports team he/she knows is gonna win, you could feasibly dump that in the #firstworldproblem basket.

Looper, from Brick (2005) and The Brothers Bloom (2008) writer/director Rian Johnson, asks a rather more pointed question. What if you were, say, a hired assassin who killed people sent back from the future? What if your job was as a member of a kind of body disposal unit, and then, say, your retirement send-off involved killing a future version of yourself to “close” the “loop.” You then spend the rest of your life living it up — girls, guys, caviar, champagne, cocaine, whatever —  before the ending you always knew was coming, came, and the younger you gives the older you a long kiss goodnight.

Joe (Joseph Gordon-Levitt) is one of these assassins, or “loopers”. Bruce Willis plays the bloke — that is, himself — he is assigned to kill. Usually it’s easy: hooded victims get spat out onto a white mat in the middle of nowhere at a precise time and bam — you only know you’ve killed yourself after you’ve done the dirty and collected the cash. But a mob led by Jeff Daniels in hammer-to-your-hand mode get upset if your old self escapes your younger self, and at that point those who can’t hurry up and kill themselves are given a helping hand.

That’s the premise of Looper, a grab bag of out-there bits and bobs that keeps throwing around ideas and a great deal of them stick. The muddier, clumsier ones involve a physiological X-Men-esque mutation concept that offers visual energy and weird thrills but does so at the expense of internal consistency and clarity.

When the movie works it works very well. Johnson’s screenplay offers fresh ways to excite and the cast, led by the bankable Joseph Gordon-Levitt and the bankable-in-the-way-of-someone-who-might-rob-his-own-bank-then-moan-about-it Bruce Willis. But there are slow and fuzzily focused bits, farm scenes between Gordon-Levitt and Emily Blunt as a shotty-wielding hick that linger too long for too little reward. Johnson crowbars in a half-baked romance when the story could have been expanding Willis’ character, which you’d ordinarily call under-developed, were it not for the fact that we spend most of the movie watching two versions of the same person.

Rian Johnson would have been better off nailing a few concepts rather than attempting so many and getting most of them more or less right. There is a whiff of Brick in some of Loopers’ dialogue, particularly the narration, which seems at first like a tantalising fusion of dystopian future and noir, but is ultimately used as a lazy bookend.

There’s a great bit of dialogue delivered by Bruce Willis, in a diner, conversing with Gordon-Levitt. We’re not going to sit here and talk about the ins and outs of time travel, he says to his younger self, because we’ll be here for hours. There’ll be straws and diagrams and we ain’t got time (so to speak) for that.

The genius of this dialogue: it was shot back from the future of the writing process, retrospectively penned after a smattering of kooky subsequent scenes had been written, perhaps to pre-empt post-movie conversation about plot holes and plausibility. We realise that well after the initial experience, recalling a memory linked to a future time in the film, which quickly becomes the past outside the film, and here we go along the merry go round, just trying to close that loop…

After all, it’s a tough slog, inventing new ways to tell time travel stories. The more clock rewinding/propelling movies we see, the less capacity they have to surprise us. Thus the desire for filmmakers to get loopier and wilder when they shake around the hour glass.

Looper’s Australian theatrical release date: September 12, 2012.