A vicious attack leaves mechanic Grey Trace (Logan Marshall-Green) paralysed from the neck down and his loving wife (Melanie Vallejo) dead. This being the not-too-distant future, something can be done about the former: a reclusive techno-capitalist (Harrison Gilbertson explicitly not playing Elon Musk) donates an experimental computer chip called STEM that can bridge Grey’s severed spinal cord. This being a film that spends at least part of its time in the action idiom, Grey wants revenge – and it turns out STEM can help with that too. The politely-voiced (by Simon Maiden) chip also functions as a kind of Siri/Cortana-alike AI personal assistant – and one that has no moral qualms about helping Grey hunt down the ex-military thugs responsible for his plight…

Some of the technological window dressing aside, Leigh Whannell’s second film as director feels like something you might have luckily brought home as part of a weekly deal from your local video library circa, oh, let’s say 1989. It shares some DNA with Paul Verhoeven and earlyish David Cronenberg, but its real shelfmates are the kind of direct-to-video cheap but imaginative actioners that used to star the likes of Olivier Gruner. That’s not a slam – the wild, anarchic creativity of DTV SF permeates Upgrade, only it’s sheathed in the concerns of today, not mired in the cultural extrapolations of a few decades back.

What that means is that the film’s world is one of massive economic disparity and nigh-constant police surveillance, where the lucky (and, it is implied, massively reduced) middle class travel between gated enclaves in self-driving cars before retiring to computer-run smart homes for evenings spent in pristine but rather soulless luxury. It’s a future that doesn’t seem too far from our own present (Alexa, order me some dystopia) and our man Grey, who takes pride in working with his hands on vintage, gas-guzzling muscle cars, is something of a throwback – a man’s man in a touchscreen world. How bitterly ironic that he becomes beholden to technology to enable the physicality he takes such pride in.

When push comes to shove, he can’t even do his own fighting and killing, but that doesn’t mean we, the bloody-baying audience miss out. In what is hands down the film’s coolest conceit, STEM can operate Grey’s body like a six foot puppet, putting him through combat manouevres that would make Bruce Lee blanch. It’s these moments that people will be talking about afterwards, with Marshall-Green looking both terrified and awestruck as his computer-controlled body rains holy hell down on all and sundry about him (the violence is stunning and occasionally shockingly gruesome).

Those moments of splatter will jar some viewers, but Upgrade refuses to be pigeonholed tonally, hopping from sleek sci-fi thriller, to gritty revenge actioner and even occasionally attempting to mine pathos from the freshly-disabled disabled Grey’s misery. It’s not a scattershot approach, per se; what it is, is deliberately weird, pulling signifiers from a range of nominally similar films (Robocop, say, or Videodrome, or even the notably more sunny Robot & Frank) but deploying them in ways that keep the viewer off kilter. Upgrade manages to keep surprising, not just in its plotting but in tone and its staunch refusal to play to the tropes.

If you spend a lot of time in the genre ghetto, that weirdness is something to be savoured. For all that, horror, sci-fi and fantasy are nominally more imaginative than your typical rank and file dramas, it can be disheartening how often films from that subset cleave to convention. Upgrade‘s chief value is that it has the courage to colour outside the lines. It’s not a game changer, but it’s a strange little slice of gruesome genre fun, and that’s pretty awesome.