You get moments with this hobby, where you mentally step away and realise exactly what you'd look like to an outsider. It's not pretty. I'm playing in a darkened room, the shades pulled tight, and I'm shouting to three other people. “HIS ARSE IS OPEN. FOR GOD'S SAKE HIS ARSE IS OPEN. SHOOT IT! SHOOT IT SHOOT IT! SHOOT HIS OPEN ARSE!”

I see myself from above. My eyes are focused on the swollen buttocks of a fat man. I've just shot him until he collapsed, almost defeated, onto one knee. What am I doing? Is this what 2,000 years of western civilisation has accomplished? Now I've circled behind him and kicked open the armoured flap covering his blubbery rear end. Humankind has split the atom, we've walked on the moon. Now three friends and I are readying our pretend guns to fire into a fat man's exposed anus.

Bulletstorm revels in its childishness. Kicked out of the super secret space army for questioning orders, riotously drunk ex-assassin Grayson Hunt seems to be aiming for some kind of accolade as the universe's worst man. Stranded on a resort world overrun by murderous weirdos, his most uttered word seems to be 'cocksucker.' The sole female character is little more than another marine, burdened with the daddy issues ubiquitous to gaming women and dressed in a pair of breasts. I should turn the monitor off in disgust, and stalk from the room.

Fundamental

I don't. I unload a full clip from my weapon into the fat man's arse instead. Three other channels of fire lance simultaneously from my teammates, riddling the man's bottom with bullets. One of us starts cackling. Mumbling now, I repeat the mantra “shoot the arse. Shoot the arse.” Eventually, the man slumps forward. He dies, and as he dies, he farts his last, a long and mournful bass note accompanied by a jet from flame from his bumhole.

As one, we cheer. We've finished wave 20 of Bulletstorm's cooperative multiplayer mode and made a man shit himself to death. We're allowed to celebrate. As a unit, we've kicked, shot, and giant-electric-lassoed hundreds of disfigured, disgusting gangsters in Anarchy mode. But 'anarchy' is a misnomer: despite the blood and guts and arses, both the cooperative-only multiplayer mode and ten hour singleplayer campaign demand restraint and discipline unheard-of in other FPS games.

Bulletstorm is maliciously playful, but it takes a while for your brain to accept that. On my first attempt, I had a gun, I pointed it at the stream of mutants who wanted to murder my space-hero, and I pressed the trigger until they fell down. It was unsatisfying. Bulletstorm's standard rifle – the jokingly named Peacemaker Carbine – is a bullethose that takes a good few seconds to wipe the head from even the flimsiest foe. Play the game as you're conditioned to play shooters – run to cover and pop your targets with concentrated gunfire – and Bulletstorm is an incredibly dull game. But you should know that you're playing it wrong.

The farting fat man isn't Bulletstorm's only trump: in addition to a gun, you have an electric leash, and a big fucking boot. Fire the leash at an enemy and you'll grab them and yank them toward you. Apply your foot to the face of a foe and they'll fly away. Both methods lead to a few glorious seconds of slow-motion, your chosen target drifting serenely through the air, their vital and squishy bits open to any punishment you fancy unloading.

I quickly slipped into a routine of applied sadism. I'd pick my victim and reach across the space between us with a line of blue energy. A moment of panic on his stupid face, and he'd be floating in my direction, legs akimbo. It'd be rude to refuse such an offer. A few shells in the scrotum, and back he'd go, booted in the direction he'd just come by my big shoe. I'd let him stand up, shake himself off, then snatch him again. At the last second, before his leaking body crumpled into my own, I'd stand aside and laugh as he sailed off the lip of a cliff. Did I mention I was standing at the edge of a cliff? I didn't tell him, either.

A shot gangster gives you ten points. A kicked-then-shot gangster gives you 250 points, and the words 'BULLET KICK' in bold yellow letters on your screen. A lassoed then-kicked-into-the-spines-of-a-cactus gangster earns you the PRICKED skill-shot and 500 points. Five gangsters, flicked into the sky by the leash's alternate fire mode and subsequently shot by a supercharged shotgun blast that reduces their scarred forms to glowing red skeletons and a pouchfull of ash, earns you more points than you can count and so many letters on the screen that you can't see what to shoot next.

That last method made me feel infinitely bigger, cleverer and filthier than the first. It gave me a desire to kill creatively, and a compulsion to get to the next fight, the next theatre of pain. The formula only breaks down later in the game, when the plot introduces feral mutants as the main enemy. They're much stupider and easier to off than their still-human compatriots, running directly at you instead of taking cover. It reduces the opportunity for clever leash-play and turns fights into drudgery.

Arsenal

The compunction to kill well is magnified by the practical application of skillshot points: they go toward all of Bulletstorm's unlocks. Those unlocks do standard things – such as increase the ammunition capacity for the Peacemaker Carbine – but they also allow access to a more unhinged arsenal. There's the gun that fires two grenades attached by a chain. Wrap the bolas around an enemy and it'll immobilise them on the spot, letting you kick them into their friends and press the detonator. Or deliberately aim wide of your target, sending one grenade into a solid object as the other briefly becomes a horrible strimmer, tearing heads and rending flesh in a small arc.

Each weapon has a nasty application. I found myself flipping between sidearms at each checkpoint – not because I'd run out of ammo, but because my brain had been cycling through new means of murder I was keen to try. Sifting through the game's recorded skillshots turned me into a macabre Pokémon master, not resting until I'd collected all the heinous ways I could possibly end a life.

Bulletstorm's world is hyper-real, like you've come home to find your little brother has fiddled with the contrast settings on all your wars. The typical shooter palette has been jolted from fashionable slate grey to 'puked a rainbow'. This has the pleasing effect of making this perhaps the prettiest game I've ever seen on PC. It repeatedly uses the Far Cry/Oblivion trick of leading you by the hand through increasingly grey interior locations before depositing you on some gorgeous precipice, the entire world stretched out before you. But these events aren't underlined by sweeping music – they're just there, to be gawped at before the game's breakneck pace whips you along. “Oh,” the game says, “this hundred-foot drop off a cliff into a churning river, lit by waning summer sunlight? That ain't no thing. Say, did you see my arses? You can shoot them.”

And somehow, that keeps the game just charming enough. Bulletstorm never tries to reach above sci-fi hokum in plot, but its writing has enough heart – something I truly didn't expect in a game containing the line “you nearly scared the dick off me” – to let it surf the heavy wave of near-disgust I'd cultivated. The first time I chuckled openly at one of Grayson's quips, I stopped and scolded myself. The second time, I let it go. By the time I was laying waste to that poor fat man's arse, I was snickering freely. That doesn't mean I ever fell in step with the game's willful crassness though: the developers' idea of a 'strong female character' is still laughable.

Bulletstorm is not art by any metric. It's difficult to defend, like a friend you take to a party who ends up pissing in a vase. You don't want to be associated with him, but shit, he provides an evening of excitement. It's a game that's very proud of the f-words it's learnt, and it uses them a lot. Fast. Frantic. Fatuous. Full-on. And yes, that other one: fun.