How does Pixar do it? How has the pioneering computer-animation studio delivered eight consecutive box-office hits beginning with its landmark Toy Story in 1995? Well, along with witty scripts, dazzling designs and wondrous technical craft, the key to Pixar’s success is that the wizards of Emeryville, California almost never repeat themselves (Toy Story 2 being the lone, welcome exception).

WALL•E, Pixar’s ninth surefire smash, is as different from their last, the Oscar-winning Ratatouille, as Cars and The Incredibles were from Finding Nemo. With each new feature, they create an entirely new world—whether undersea, underground, American pastoral or French provincial. This time around, they’ve envisioned two worlds: a post-environmental-apocalypse Earth and a hilariously hedonistic spaceship refuge. And within those strikingly imaginative environments, writer-director Andrew Stanton (Finding Nemo) offers up a tale that’s equally satisfying as science fiction, cautionary satire, gentle love story and purely visual comedy.

WALL•E (short for “Waste Allocation Load Lifter Earth-Class”) is a trash-compacting robot, the only such machine left behind after humans fled Earth some 700 years earlier. For a bot, the little guy has a lot of personality: He scavenges knickknacks like a flea-market addict, and constant viewings of an old videotape of Hello, Dolly! help him get through the day. His sole companion is a feisty cockroach (yes, they will surely survive us) who always emerges intact even when he falls under WALL•E’s treads. Then, one momentous day, a giant spaceship arrives and deposits a sleek, egg-shaped robot dubbed EVE (for “Extraterrestrial Vegetation Evaluator”), assigned to search for signs of organic life. WALL•E is instantly smitten, but he’s like James McAvoy cowering before Angelina Jolie in Wanted, as EVE is quick to fire her powerful laser weapon at anything suspicious. But gradually, WALL•E’s endearing, persistent attempts at courtship win over EVE and a bond develops—until WALL•E shows her the young plant he’s been tending.

Programmed to obey orders, EVE commandeers the sprout and is soon on her way back to Axiom, the giant deluxe spacecraft that shelters the human race and is like the ultimate cruise ship, where robots tend to every want and the population has grown so obese they can barely stand. The lovestruck WALL•E has tagged along, of course, and his efforts to reunite with EVE create chaos in the colony. But the bots find an unlikely ally in the overfed captain of the ship (voiced by Jeff Garlin of “Curb Your Enthusiasm”), who realizes that EVE’s discovery signals that it’s time for the human race to shape up and return to their homeland.

Just as Pixar made a rat in the kitchen palatable in Ratatouille, the studio takes big risks in WALL•E that pay handsome dividends. The first half-hour of the film forgoes dialogue, with the exception of the robots’ beeps and blips and their calling out each other’s names. Stanton and co-writers Jim Reardon and Pete Docter here evoke classic silent comedy, setting up innumerable clever sight gags and achieving surprising expressiveness within the physical limitations of their adorable mechanical lead. (Those big binocular eyes are a huge help, as is the resourceful sound and vocal design of veteran Ben Burtt, the man behind Star Wars’ iconic R2-D2). The vision of a barren Earth is daringly dark for a G-rated family feature, but WALL•E’s antics go a long way toward lightening the mood.

Once the story moves to Axiom, the movie becomes an absolute riot of farcically futuristic production design, with its portrait of an absurdly pampered populace, and the cracks in the system revealed by various robot rejects. At times, the action is almost too frenetic to absorb, but kids will be delighted by the bedlam while their parents ponder this sardonic forecast of the future.

Special mention should go to Thomas Newman’s consistently delightful music score, and the unexpectedly poignant use of clips from Hello, Dolly!, a legendary movie flop that now finds a whole new longevity thanks to this classic Pixar showcase. Hey, if there’s hope for Hello, Dolly!, maybe Planet Earth has a chance too.