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The scariest noises in Hell Let Loose: Vietnam are the quietest. The dry-rattle of gunfire is too constant, and helicopters' telltale thwup-thwup gives plenty of warning before dropping fresh troops. Maps are big, so sound is one of the best tools for gauging the flow and geography of a match. When the fighting isn't as loud – if you're separated from the capture point or creeping through the jungle behind enemy lines – rustling leaves and snapping twigs may as well be fireworks.

My reaction speeds are slow, so when that crunch is a half-second warning, I'm often the first to die. But that's a fair price to pay for atmosphere. The best FPS games don't underestimate immersion: Marathon sparked my imagination earlier this year, and now Hell Let Loose: Vietnam is doing the same; pairing Battlefield-style 50v50 matches with gritty realism and more emphasis on teamwork.

"From day one, we wanted to be immersive and intense," says game director Paul 'Rushy' Rustchynksy. "We're trying to capture moments of 'If you put yourself in the boots of this conflict, how would you feel?' You would feel like you're exposed at all times, at any moment you could die."

Hell Let Loose: Vietnam doesn't hone in on the human cost of the Vietnam War, as many games and films have done before. Instead, its source material funnels directly into how the game is experienced as a shooter. "Stress can really affect how you play. It's not the sort of thing where you're running around on maps at 20 miles an hour, dashing between gaps," Rustchynksy explains. "You're thinking about every move you make. You're leaning around corners. You're talking to your squadmates about where [enemy] infantry are, and you're never running headfirst into things."

"Well… Maybe some players do. Initially."

(Don't) run through the jungle

Hell Let Loose: Vietnam's setting creates a different dynamic to Hell Let Loose. More weapons are fully-automatic, sightlines are shorter, and factions have unique tactics to reflect their real-world counterparts. The North Vietnamese Army can dig tunnels to cross areas undetected, while the US Armed Forces use helicopters for similar utility.

"The pacing of the game is generally faster because there's more modes of transport," says Rustchynksy, "and [there's] generally much more close-quarters combat this time around, whereas World War 2 was much further away."

But the "heart" of Hell Let Loose: Vietnam, Rustchynsky argues, is its asymmetric design. I agree: having two functionally unique factions brings out the character of both sides, whether it's pulling off the perfect flank as the NVA or being flown over the jungle and dropped into the frontline in a U.S. chopper. It's part of a broader tactical layer (each team is led by a commander, who gives orders through squad leaders) and feeling like a small cog in the machine lends itself well to immersion.

At times, merely being part of something bigger is enough to get the heart racing. I recently played as a crewman, operating an unwieldy tank turret while my friend managed the armor's gears to drive us to the frontline and support infantry. We won, and it was even sweeter because I could point exactly to how our contributions helped. Sometimes those moments are more dramatic: in the final throes of that match I fired a frag round into a descending helicopter's cockpit, taking out a full flight of troops who would have reinforced the capture point's defenders. The game after, I was a sniper separated from my spotter, and spent 15 minutes picking off marching troops – at one point lying in a bush to hide from a passing tank – before we could link up in friendly territory.

"It's these little things that really stand out," says Rustchynksy, speaking to my favorite part of the game: the stories you get from playing. "It's not something you can overly engineer. It's just making sure that the tools and things we allow the player to do inside the game [create a] free-form, sandbox-like experience [...] Where these emergent moments can happen."

"It's also really rewarding to see when some of the strategic plans come together," agrees Sam Warren, development director on Hell Let Loose: Vietnam. "Bits like that are magic."

The original Hell Let Loose brought in many players from beyond the usual military-sim crowd, and in the years since, the likes of Arc Raiders and Marathon have pushed punishing shooter mechanics to the mainstream. There's more interest in traditionally 'hardcore' experiences, especially as many players jump in and find there's a lot more to the experience than shaky aim and quick deaths.

Put simply: more people are trying games they aren't immediately good at. I ask Rustchynksy whether that's good for Hell Let Loose: Vietnam, and while he believes it is, he seems more enthused by the prospect of generally harder games. "I think this is a fantastic trend in general, because if you take away too much friction from games, it removes so much of the enjoyment. You need that little bit of friction so that when something satisfying happens, it feels really good. And also typically with games that have a bit of friction, the ceiling for mastery is often a lot higher."

In some ways, Hell Let Loose: Vietnam is harder than conventional multiplayer shooters. A hidden sniper or mortar team can send you back to HQ without ever being seen, and it takes confidence to jump into a random squad and follow orders. But when you take a step back, its chewier features are in service to an immersive and more deliberate experience, rather than simply making a tough shooter. Wits and vigilance pay off more than being quicker on the trigger – though on many occasions I've wished I was faster – and if you slow down to meet Hell Let Loose: Vietnam at its own cautious pace, you'll find there's oceans more to discuss beyond difficulty.

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