Nostalgia often seems the fastest-changing thing on earth. Before we know it we are feeling gooey about 1982, which a nano-moment ago we were living in while feeling gooey about 1962, which a giga-epoch ago... And so on. Son of Rambow is a rainbow-coloured UK comedy about childhood, celebrating that innocent English Eden in which Britain had just won the Falklands war and movie piracy was a gleam in the eye of the country’s youth. Kids who couldn’t see Sylvester Stallone’s hot-ticket Rambo at the local cinema could beg or borrow a video bootleg.

Innocent? Edenic? Many commentators, including anti-Thatcherites, have spent 20 years trying to shoot the 1980s down in flames. But childhood is childhood. It doesn’t respect the social-political doomsayers or badmouthers, contemporary or hindsighted. It just gets on with the job of play and make-believe. So 10-year-old Will (Bill Milner) falls in love with Stallone-Rambo soon after seeing the scratchy video made from the movie screen by semi-delinquent schoolmate Lee (Will Poulter). The two boys start making their own Rambo(w) movie in homage. They hope it will ticket them through to fame on telly or better.

Writer-director Garth Jennings (The Hitchhiker’s Guide to the Galaxy) has cleverly made Will’s family Plymouth Brethren. So the boy is forbidden to watch TV and regards any moving picture as an illicit and thrilling miracle. Jennings recognises that the marvellous often grows from stony ground (just as magical realism thrives under dictatorships). So the pedantic pedagogues in school, the pious parents, the grim semi-industrialised landscape (cooling towers, ruined factories) and Lee’s bullying spiv of an older brother all help to provoke and propel the imagination. The rich daftness of the boys’ DIY movie is filled out with flying dogs, limb-endangering stunts and Eric Sykes (no less) wigged up in his character’s care home to play a PoW camp inmate. There hasn’t been this much surreal fun with homemade cinema since Be Kind Rewind.

It wouldn’t be fun at all without charm, of which there is oodles, especially in the performances. Milner is a stick of vitality: his face and eyes only need their touchpaper lit to fizz and sparkle. Poulter plays Artful Dodger to his Oliver, a frowning hellion capable of Damascene grins of mischief. The third star is Jules Sitruk, whose French exchange student has a Gallic cool – black blouson, drainpipe jeans, teenage stipple of moustache – that blows away the Brits, at least until he shows he can’t cut the Dijon as a film actor. After arrogantly muscling in on the Rambow project, his stardom bid is left twitching on the cutting-room floor. (Even a kid comedy must get in a kick at the French, at least in the historical safe zone before the entente formidable.)

Cinematographer Jess Hall must have been told to step up the colour saturation. The film’s England is permanently painted with rainbow colours. But that is how we like to remember childhood, isn’t it, whatever was going on at the same time in that dull, responsible, grown-up dimension called history?

Childhood exists at a quite opposite pole in Funny Games. It is doomed and sacrificial along with everything else. This is Michael Haneke’s American remake of his same-name Austrian killer thriller. Back in Cannes in 1997 – dare to be nostalgic about that occasion – this tale of mental and physical torment, in which two young men hold captive and persecute a family of three in their lakeside holiday home, sent its audience reeling into the night. One critic said to me: “The film is like turning the gas up in Auschwitz.” Haneke himself, at a press conference, said that normal people would leave the film before the end. Only those who needed it would stay.

Does anyone need the remake? It is a virtual shot-for-shot reconstruction. It is acted to the hilt – near-literally as each impalement strikes home – by Tim Roth (dad), Naomi Watts (mum) and Michael Pitt (chief tormentor). Devon Gearheart as the ill-starred son, weeping with panic and wide-eyed with fear, gives the best child’s performance in a prodigious week for kid actors. The new film, toying with its audience as fiendishly as the old one, dares again the Pirandellian frame-breakings: here a character’s sudden aside to the camera, there the surreal rewinding of a scene to erase a re-considered atrocity.

Yet the word buzzing in my brain is “cynical”. I never felt that of Funny Games 1. That was an original, cruel but devastating. Funny Games 2 is a robot version, brought out to popularise the death-machine for the western market. We are being sold a makeover that looks the same, sounds the same, even – to a degree – functions the same. But it cannot bring the same freshness to a different age and audience, jaded today with torture porn and, in Anno Nintendo, unlikely even to find a fresh, chilling novelty in its tricks with narrative.

Daniele Lucchetti’s My Brother is an Only Child is about an Italian family, which means everyone shouts at everyone. When they don’t, Lucchetti fills the soundtrack with 1960s songs, determined to leave no gap in a film that is a giant advertising space for yesterday’s pop culture and agit-heroism. Somehow it all succeeds in being intelligent and sharply satirical in its portrait of a headstrong youth (Elio Germano), raised in Latina, Rome’s Mussolini-built satellite town, who converts during an eventful decade from fascism to communism.

Screenwriters Sandro Petraglia and Stefano Rulli, adapting a bestselling novel (Antonio Pennacchi’s Il fasciocomunista), bring the time-scoping skills honed in their great social-history fresco The Best of Youth. The hero Accio and his Marxist older brother (Riccardo Scamarcio), a rake with rabble-rousing rhetoric, alternate between hugging and punching each other. Mum (Angela Finochiarro) grows older by the minute while Accio’s father-figure mentor, a demon-driven fascist, grows younger. The country is in ferment, as Italy always is. There is a lovely sense of a single decade speaking for eternity, of eternity responding with “You speakin’ for me?”, and of a time when everyone strove to hijack and control history before it hijacked and controlled them.

If the picture of mad people in Park Chan-wook’s I’m a Cyborg were any more sugary, we would risk tooth-rot. Why does cinema sentimentalise the mentally disturbed? It is tragic – isn’t it? – that a young female factory worker (Lim Soo-jong) tries to kill herself at the assembly line, then lands in a psychiatric hospital where her alienation finds companionship with a capering, rabbit-masked youth. Perhaps the Korean director who made the stylishly violent Oldboy and Lady Vengeance is changing direction and saying “No more Mr Nasty Guy”. His fans will respond, “Why change a winning streak?”

In Awake, Hayden Star Wars Kristensen plays a creepy businessman who remains conscious under sedation during heart surgery. This begs or raises too many questions. How do we know, from his acting, when Kristensen is conscious and when not? And are heartless businessmen the right people around whom to build cardiac melodramas?