Sentient robots and invading overlords rub shoulders with bent coppers and globe-trotting military men in our list of the biggest and best movies hitting UK screens in March and elsewhere in the not-too-distant future. Neill Blomkamp – the writer-director behind District 9 and Elysium – delivers a third sci-fi flick in the shape of Chappie, set in the near future when a mechanised police force patrols the streets of Johannesburg.