There’s a natural inclination to praise American animated pictures that dare to break out of the standard kidvid straightjacket and conventional artistic modes, and Shane Acker’s expansion of the film-school short that was nominated for the Oscar in 2005 will be embraced by many simply for doing that. Unfortunately while visually arresting, “9” is narratively a pretty familiar piece, and at once too mature for children and too childish for adults. At less than eighty minutes it still seems overlong and obvious.

The script by Pamela Pettler, based on Acker’s story, is set in a dusty, post-apocalyptic world where humankind has disappeared in a destructive cataclysm. There a small critter resembling a cloth bag in humanoid shape, with big mechanical eyes and the number “9” printed on its back, comes to life. Venturing into the desolation, it encounters another creature like itself but older and more experienced, “2” (Martin Landau), which not only gives it voice (Elijah Wood’s, in particular) but saves it from a ravenous machine that looks like a skeletal dog by sacrificing itself. “9” then meets another of his kind, quiet, recessive “5” (John C. Reilly), who takes him to the community ruled by priestlike elder “1” (Christopher Plummer) that includes bruiser “8” (Fred Tatasciore), spectral artist “6” (Crispin Glover), silent twins “3” and “4,” and athletic female “7” (Jennifer Connelly).

“9” clashes with “1” over strategy, arguing that they must go out into the wild to save “2” while “1” insists that his policy of caution and concealment is the right one. But “9” prevails on the others to follow him, and ultimately the group must confront a huge, reanimated machine—the apotheosis of the technology through which, as some found film footage reveals, an ambitious fascistic dictator hoped to rule the world but that turned on its designers. The film also discloses that “9” and his cohorts were created by one of the scientists who built the machine but regretted doing so—and who poured parts of his soul into his numbered creations to that they would possess the spark of humanity that can defeat the monster and begin life anew on the planet, though in a rather different form.

Acker shows considerable imagination in the design and execution of the film as a visual exercise. Though “9” and his fellows aren’t terribly different from the sort of rag-doll critters that have appeared in lots of short animated films, they’re engaging enough, and the voice talent lends them distinction. More impressive still are the ruined, desolate vistas, and especially the villainous machines, that skeletal dog first of all but finally the ultimate mechanical destroyer, which resembles something like a huge spider with one glowing red eye that can literally suck the life-force from the tiny heroes and literally consume it.

But the skimpy plot of “9” doesn’t do the visuals justice. It’s basically no more than an extended, and far gloomier, variant of the simple chase that drove virtually all the old Warner Brothers cartoons. But they were only a few minutes long, and had none of the dour earnestness of Acker’s construct.

Besides which, the script lacks the rudimentary logic that even an animated sci-fi tale needs. For example, it’s “9” that brings the monster machine back to life, apparently driven by a memory implanted in him by his creator. But why not simply leave the thing eternally dormant instead? There may be some rationale behind this, but it’s certainly elusive. Then there’s the matter of the life that the numbered sock puppets represent. Yes, it has a trace of humanity to it, but will it stop with them? (In other words, can they reproduce?) In this respect, the mission of Wall-E, a not dissimilar entity, made a lot more sense—and was much more fun to watch.

There’s no denying that “9” has a fascinating look, and it’s understandable that a couple of guys like Tim Burton and Timur Bekmambetov, who specialize in entrancing appearances, should have played an important role in helping Acker realize his vision. But it’s equally clear that Pettler, who worked with Burton on “Corpse Bride,” hasn’t supplied equally compelling content. The outcome is a film that’s like a box that’s brilliantly wrapped but empty. It leaves you feeling more than a trifle unsatisfied.