South African director Neill Blomkamp joins a long queue of filmmakers who have wrestled with the question of whether highly evolved robots have rights on par with those of their human creators. The director of the estimable District 9 and the halfway successful Elysium adds allegory to an inquiry that has been explored with greater coherence in such films as Bladerunner, Short Circuit, RoboCop and A:I. The title refers to the South African term for a young man, there are references to police violence and racial inequality, and the movie is set in a deeply divided Johannesburg that doesn’t appear to have needed too much dressing to appear equal parts posh and seedy.

Chappie is a feature-length expansion of Blomkamp’s short film Tetra Vaal. In the innards of the dystopic city, punk gangsters straight out of Mad Max steal a specimen from the government’s highly effective robotic police force. The cyborg, named Chappie by his human “mommy” Yolande (one half of South African hip-hop duo Die Antwoord), unfortunately comes with baggage in the form of his creator Deon (Dev Patel). Hamming in a manner that must surely be illegal in some places, Patel’s Deon is the textbook creator, who works for a private corporation but dreams of giving the world the first robot with aesthetic attributes.

Much to Deon’s horror, Chappie’s new family, comprising Yolande, Ninja (the other half of Die Antwoord) and Yankie (Jose Pablo Cantillo), would rather have the robot rob banks than paint blue skies. Some of the cock-eyed humour lands when it should, such as in the sequences when Ninja tries to make Chappie a regular homie with his own stash of bling. Chappie is voiced with ET-level endearment by Sharlto Copley, the delightful South African actor whom Blomkamp introduced in District 9. Had the screenplay by the director and co-writer Terri Tatchell not thrown in the narrative strand of Hugh Jackman’s jealous co-worker, who tries to sabotage the programme that originated Chappie to push his own design, the movie would have been sharper, wittier and better assembled.

Blomkamp and Tatchell aim for the wicked subversions that elevated Paul Verhoeven’s RoboCop, but Chappie shoots in too many directions. As wasted as Jackman is Sigourney Weaver’s corporation boss, who appears to have been cast simply as a tribute to her appearance in such sci-fi classics as the Alien films and Avatar. The hip-hop duo are a hoot, compensating for their rawness with convincing swagger. The robot itself is beautifully realised, moving without a trace of awkwardness among the humans it so badly wants to emulate and finding the time in the middle of the relentless action to commune with a street dog – a stray moment of tenderness in an overly busy movie that needed more of them.