Want to see how it feels to be in the middle of the craziest action this side of "The Matrix" and "The Raid"? New movie "Hardcore Henry" was filmed entirely from a first-person point of view, and it's a riot of insane stunts described by its director as "a cross between a theme park ride, a film, a video game and a rock concert".

It's in theatres now, so here's six things you need to know about "Hardcore Henry".

It was shot on a GoPro

The film was shot almost entirely using the small and portable GoPro Hero 3 camera mounted in a custom camera rig and strapped to the face of a cameraman.

Thirteen different people wore the rig, depending on the shot, including stuntmen, cinematographers and director Ilya Naishuller himself. The first version of the rig was made of metal -- described as a "medieval torture device" by the director -- but was refined into a 3D-printed plastic version.

To capture the complex choreography, individual takes could be up to seven minutes long. The unusual filming technique involved "nonstop trial and error," according to Naishuller.

Check out this musical behind-the-scenes video to get a glimpse of the balls-to-the-wall stunt work that went into creating the film's bonkers action:



"It was a nonstop learning curve," Naishuller told us, shortly after the movie's debut at film festival South by Southwest. "The stuntmen had it very difficult, the actors had it very difficult. You have to relearn your craft to get the results you need".

Enlarge Image STX

During filming, the crew began to feel the responsibility of not only shooting a very unusual film but also the potential for this Russian-made movie to be seen globally. "Even though most of us had never worked on a feature, we just had this strong belief that this was going to be something special," said Naishuller. "There was an electricity in the air".

The guy from "District 9" is in it

The film stars Sharlto Copley, star of "District 9" and "The A-Team". Copley compares "Hardcore Henry" to his breakthrough film, the surprise hit South African sci-fi drama "District 9", because the Russian production team "want to show they have something to offer this medium", embracing "opportunities Hollywood hasn't jumped on".

According to Copley, "Hardcore Henry" was "unquestionably the hardest film I've made in my career by a long way... It was meant to be 45 days and it took 120 in the end. I went back to Russia three times".

The film also stars Haley Bennet from "The Equaliser" and Tim Roth from "Reservoir Dogs".

It began as a music video (or two)

The concept for the film began in two first-person music videos by the Moscow band Biting Elbows, "The Stampede" and "Bad Motherf****r". Naishuller, the band's front man, directed both videos, in which an unnamed protagonist attempts to steal a teleport gadget from a horde of henchmen. There's plenty of fighting and shooting, along with fighter planes, snowy mountains and chasing across rooftops.

Here's part one of the story, "The Stampede". Be warned, it's pretty violent...



Between them, the videos have racked up nearly 40 million views on YouTube and even more on Facebook and across the Web. Here's the follow-up, which adds to the violence a sprinkling of very rude words...



The videos attracted the attention of "Wanted" and "Nightwatch" director Timur Bekmambetov, who backed Naishuller to expand the idea into a feature.

The star thought he'd killed a stuntman

One sequence sees Copley driving a car when it's attacked by bad guys, a sequence filmed on the Russian streets as the regular traffic went past. When one stuntman was dispatched, the car went over a bump and Copley thought he'd run the man over until he was able to drive back round the block to find out he was fine.

It might make you sick

Copley jokes that the front four rows of the theatre are "the splash zone". The film can have a physical effect on viewers, and not just because of the over-the-top bloody violence or the juvenile humour. The constant motion can at times be a bit much, though Naishuller claimed it could have been worse, admitting "I get motion sickness, so I wanted to make sure I could watch it!"

If you like the sound of the roller coaster ride, then sit up front, but if you're less sure, then sit a bit further back and you should be fine.

There might be a sequel

Naishuller admitted that at times during filming he thought "I never want to do this again". That doesn't mean we've seen the last of Henry, however, as Naishuller already has an outline for the sequel.

"I would jump at the chance to do a sequel," said Copley -- as long as it was with Naishuller and his crew, he laughs, because they're the only people who know how to do it.

"Hardcore Henry" is in theatres now.