For all the critical acclaim and awards recognition that Pixar has earned, animation is still largely perceived as a form of children's entertainment. The list of animated films that have received something harsher than a PG rating from the MPAA is short and, with little exception, commercially insignificant. As well intentioned as it may be, the Academy Awards' Best Animated Feature honor has felt like the kids' table at Thanksgiving, something cute and charming but separate from the main feast.

When respected filmmakers like Wes Anderson (Fantastic Mr. Fox) and Tim Burton (Corpse Bride, Frankenweenie) have embraced the medium, expectations have been somewhat different, with critics approaching the works as part of their auteurs' oeuvres. But even those movies were rated PG and treated to wide release by major studios. A far less conventional and more challenging piece of animation is Anomalisa, a stop-motion romantic dramedy written and co-directed by Charlie Kaufman, the Academy Award-winning scribe of Being John Malkovich, Adaptation., and Eternal Sunshine of the Spotless Mind.

The film opens with chatter. Unremarkable, genial small talk fills the soundtrack as we see an airplane fly across the sky. Our protagonist is Michael Stone (voiced by David Thewlis), a middle-aged, British-born, L.A.-based authority on customer service. Michael, whose book is celebrated as gospel by those in the field, has traveled to Cincinnati for one night in order to deliver a speech at a customer service convention the following day.

Kaufman and co-director Duke Johnson, a young man seasoned in stop motion shorts and television (including Adult Swim's "Moral Orel" and "Mary Shelley's Frankenhole"), are in no rush to present something extraordinary. But by simply showing us a plane landing, a stroll through an airport, and a cab ride during which Michael is encouraged to visit the zoo and try the local chili, the film has already established a unique tone and unusual outlook. Michael checks in to the swanky Fregoli hotel and is unnecessarily led to his room by a valet, who points out the luxurious room's standard features.

The lonely, melancholy Michael looks up an old love and invites her to join him for a drink at the hotel's bar. The two haven't seen each other in eleven years and you might expect their reunion to be the focus. But it is short-lived and unpleasant. By this point, you've already noticed that with the exception of our protagonist, every character in the film has the same face and the same voice (Tom Noonan, who stole scenes in Kaufman's underrecognized 2008 directorial debut Synecdoche, New York). I feared I was somehow mistakenly being shown a work-in-progress version with temp track recordings at my month-early screening, Noonan's masculine tone an unlikely sound to come from a waitress and Michael's wife on a phone call home.

The purpose of that design becomes clear when a freshly-showered Michael incidentally trots down his 10th floor hallway and encounters two star-struck fans who have driven down from Akron to hear him speak. One of the two women is named Lisa and voiced by Jennifer Jason Leigh. She has some kind of barely noticeable facial scar and a voice distinctly different from the masses. Michael has at least his second Belvedere martini of the evening with the two apple mojito-drinking women and then pulls off the awkward feat of inviting just Lisa back to his room.

The self-deprecating, long-single Lisa wins him over with her renditions of Cyndi Lauper's "Girls Just Want to Have Fun." The two, until recently strangers, sleep together and not just in the old-fashioned fade-out, sunrise way. Their awkward, meaningful sex is shown in full in graphic, honest detail, starting with him performing cunnilingus on her. In the morning, after being convinced that the world is out to keep them apart, Michael plans to hold on to Lisa, who he has nicknamed Anomalisa, a portmanteau combining her name with one of her favorite words she learned from reading his book.

Adapted from a 2005 "sound play" and partially crowdfunded on Kickstarter, Anomalisa is likely to be both revered by critics and avoided by the general public. Despite the success of Adult Swim and like-minded satirical TV cartoons, adult-oriented animated movies are few and far between. There are Richard Linklater's two millennial rotoscoped works, Trey Parker and Matt Stone's South Park movie and Team America: World Police, and almost nothing else to use as a recent reference for how this R-rated American film could fare. Naturally, Kaufman's film is closer in spirit to Linklater's two 'toons than the mainstream Parker and Stone farces.

Anomalisa is intelligent, existential, and offbeat. There is no reason to expect anything else from Kaufman, who is one of the most creative storytellers in modern cinema. Kaufman's first two works, Being John Malkovich and Adaptation., caught people's attention with their original and strange/beautiful ideas. Both of those Spike Jonze-directed dark comedies fall apart as narratives in their final acts. Kaufman succeeded more on Eternal Sunshine, his Oscar winning script for director Michel Gondry. Anomalisa ranks up there with that triumph, for it is able to fully sustain its ideas cohesively and coherently. There is little room for error in animation, particularly in painstaking stop-motion. The film is taut and compelling throughout. When its end arrives, a tad abruptly, you are sad to have to leave, but grateful the film hasn't overstayed its welcome with strange twists and prolonged surrealness.

Anomalisa is rich with ideas and full of humanity. Kaufman shows a great interest and appreciation for mundane, universal experience. His wit creeps into the driest and most ordinary of exchanges, aided no doubt by the medium. Animation is regularly embraced for its ability to convey fantastical things. Too often, those fantastical things are animals who talk and crack wise. Kaufman and Johnson see the potential for telling a mature and realistic story in stop motion and they realize that potential quite beautifully. Some viewers undoubtedly will grow uncomfortable at the material. More screentime features full frontal male nudity in this than in all the Judd Apatow movies put together. And that awkward sex scene could prompt walkouts from those who have entered with the wrong expectations and could not have foreseen such a turn coming.

But it's easy to appreciate Kaufman putting his story over the general public's comfort levels. There is nothing gratuitous about the content and none of it seems designed merely to shock. The film even has fun with its character design, which places seams through characters' eyes and at their jaws, as if they are all wearing masks, or at least eyeglasses. Anomalisa could have been made in live action, but it would not be the same movie, nor would it be as endearing, imaginative, and striking as it is.

Anomalisa is the first real wild card in the 15-year history of the Best Animated Feature Oscar. It has the backing of a major studio -- Paramount Pictures -- with only one other serious contender (The Big Short) to promote. It has a respected and decorated filmmaker at its helm easily distinguished from the animation figures who have never dabbled in live-action fare. And it has nothing really in the way of precedent and direct competition. Inside Out has seemed like the Animated Feature frontrunner from the moment it was released. I remain confident it will add to Pixar's record win total and deservingly so, for it is a genuinely great film. But Anomalisa seems too substantial and critically admired to be ignored the way that, say, Linklater's rotoscoped rambles were. There even seems to be a chance for this to sneak into Screenplay contention, as certain animated films have before. But I wouldn't expect such recognition to mean all that much for what is likely to be a modest bottom line formed by the open-minded arthouse sect.

Buy Anomalisa from Amazon.com: Blu-ray + DVD + Digital HD / DVD / Instant Video