My breath catches in my throat as my teammate crawls through the vent on his stomach just ahead of me. Everybody else is dead, and the guards protecting the facility are now pacing the halls looking for us, their footsteps echoing. We edge forward in silence, waiting for the single noise that will give us away and earn us a fatal case of lead poisoning.

Intruder is tense. It might be the scariest first person shooter I’ve ever played. It’s a game about learning fieldcraft, a certain way of doing things. That’s why I think it’s one of the best multiplayer shooters I’ve played.

The kill notifications offered in other shooters are absent here, so if you’re feeling bold you can play dead, but one of the things you learn quickly is to put a round into the head of any prone enemy. Just to be sure.

There’s a simplicity to it: there are two maps with different objectives. In one, the intruders must infiltrate a clifftop facility to steal one of two briefcases. In the second, intruders must assault a different clifftop facility to hack some computers. The first one tends to be the most played whereas the second is smaller and more direct. There’s a little less nuance to your bloody heists. When you die you die for the round, so every firefight is incredibly tense. Considering there’s only a pair of maps, it’s still incredibly replayable and I’ve spent many hours running around stealing and protecting briefcases.

The guns are somewhat plain—you have a silenced pistol for shooting people quietly, a submachine gun that points itself at the roof if you pull the trigger for more than a second and if you’re lucky you might pick up a sniper rifle that requires you to crouch and stop moving before you can get any sort of accuracy. They all have their uses and fit into the game well, but combat is a brutal, clumsy thing, defined by the terrible physicality of your characters; jumping up onto a railing will often lead to you slipping and falling to your death, while running around a corner can lead to you falling over and sliding across the floor. Explosives and bullets will, in addition to doing damage, knock you to the ground. It’s the first shooter I’ve played that’s managed to make me feel like the fleshy useless lump that I am.

You’re given a collection of tools: mirrors to look around corners, electronic motion sensors, C4 and finally a lockpick to open the randomly locked doors that populate the maps. These tools all have their own tricks and tips, and there are plenty of strategies that you’ll slowly pick up over time.

Learning these strategies takes time and it’s a tough game but by selling the game in small quantities at a time, Developer SuperBoss Games is ensuring the level of engagement with the community remains high. New players are slowly introduced to advanced concepts and most players on the official forum and in-game are patient and friendly. Because all servers are handled by SuperBoss, players looking to cause trouble can find themselves banned from the entire game.

When these systems mash against each other you start to see some fun moments. Take for example, the “vent swap” play I was describing in the first paragraph. Here’s how it works:

The vents located near the “intruder” spawn point will take you directly into the server room containing one of the cases the intruders can steal to win a round. By design, the drop from the vent to the floor of the server room is one way, meaning that once you’ve grabbed the case you can’t make a quick exit. However, any teammate can take the case from your back. This means enterprising players soon learnt that by grabbing the case and clambering onto a table in the room means that a teammate still in the vent can grab your case and scurry off back into the vents.

I’ve videoed the process here so you can see how this looks when it works:

Communication is terse because you talk in-game and speech can be heard by anyone close enough, friend or foe. If you want to talk to someone who isn’t stood within bellowing distance you have to put your gun away and get out a radio which means you’re both unable to defend yourself and loudly broadcasting your position.

Shooter games are often accused of homogeneity. Military man-shooters blend together in a horrible mess of gun porn and faux-realism as your jingoistic heroes battle the forces of evil—every game merges into one, every round blurs together. Intruder is an outlier. I’ve got vivid memories of the time I jumped down from the roof only to slip on a railing and die ingloriously before a single round was fired. Then there was the time I got shot and fell into the sea far below the house only to survive and climb back into the building. Trailing blood behind me and clinging to the last vestiges of life, I stalked the house taking out the Intruders one by one with a silenced pistol as they started to audibly panic. “Dragon, anyone?” the last player tried on his radio, plaintive now as he realised how the 10-minute round had played out.

Moments like this are supposed to be what defines games, aren’t they? The bits where you have to tab out into Facebook Messenger to tell your friend what just happened, a 1am “you had to be there” explanation of how you’re the greatest armed assailant the world has ever seen.

It’s been a long time since shooters had a real jump forward. Where most are content to drip feed upgrades to anaesthetise you to the hours you’re pouring into them, Intruder dares to be different. It’s never going to ascend to the same level as Battlefield or Call of Duty, but that’s OK. Games like Intruder matter because they try new ideas. The level of complexity really is astounding and that’s going to scare a lot of players off, but it’s also already drawn in a loyal community who really buy into the vision of the game.

Sadly I can’t be one of them, because games journalism is a lonely road filled with new games and fleeting communities, but I imagine myself dropping back in a month or six from now and being welcomed back with open arms and automatic weapons fire.

I’m not foolish enough to believe Intruder will change the world. The future of games will probably always be blockbuster murder-fireworks. But I’m happy to sit over here forgetting which button activates my lockpick and getting killed.

Follow Jake Tucker on Twitter @_Jaketucker.

RELATED: Gamers Next Door Pam and Amelia are on a ‘Mario Maker’ Mission