[A brief warning: The Binding of Isaac is not for the faint of heart. The simple, stylised nature of its art-style mean that it is unlikely to shock and appall many, but at its core this is a game that doesn’t care much about your sense of taste. It contains cartoony images of and references to: drugs, satanic worship, medical gore, sexuality, abortion, and violence against children. As I said, it’s unlikely to do more than leave a strange, perhaps unpleasant, taste in your mouth, but if you consider yourself especially squeamish perhaps consider giving this a miss. Right then, on we go]

Isaac is an ordinary child, and while he is bullied at school his family life  is far more problematic. His father seems to be absent, perhaps he always has been, and his mother is remarkably unbalanced, to say the least. One day Isaac’s mother hears the voice of God, and he tells her that Isaac is corrupted; that he must be protected from the sin that runs through the world. Isaac’s mother gladly attempts to purify Isaac – she removes all his toys, possessions, indeed his clothes, and shuts him up in his room. But God speaks to her again, and demands that as a show of faith she must sacrifice Isaac. She gladly attempts to do so, her faith is so strong, but just as she is bearing down on Isaac with a butcher’s knife he escapes – down a trap door and into the basement. To safety.

You play the part of Isaac, and you need to keep him alive. The basement is vast and labyrinthine, and deep. You have to move from room to room, descending deeper and deeper into the basement, though to what fate you can’t know. You certainly can’t go back upstairs, at least. But the basement isn’t really safe – Isaac’s mother doesn’t appear to be around yet, but there are other threats that may prove just as deadly.

And they will prove deadly, because this is a hard game. Isaac only has a small amount of health, and health-restoring items can be rare. But when Isaac dies, and he will die, he’s dead for good. There are no extra lives, checkpoints, or second chances – make one wrong move and Isaac is gone. When this happens you’ll have to start the game over again, forfeiting all your progress and anything useful you may have been lucky enough to find. This makes the whole affair very tense at times, and you’ll never feel like you can drop your guard. And that’s a great thing: you’re never coasting, because you know that every room you enter could be your last. You start making plans and contingency plans, and worrying about just how you’re going to get past the next challenge. It also isn’t frustrating when you die, and there are two reasons for this: (1) even though you’ll be losing all your progress each time you die a full run-through of the game will only take between forty-five minutes and an hour, so you’re never really losing too much, and (2) it’s filled with so many secrets, items, and different possibilities that every game feels new and exciting.

Isaac is understandably upset about his situation – his mother tried to sacrifice him, the kids at his school bully him mercilessly, and even now the creatures in the basement want him dead. As such Isaac is perpetually in tears, and at first Isaac’s only way of fending off his aggressors is, in fact, to cry; his tears will damage any enemy he comes across. And as you explore the basement, and the deep caves found underneath, you’ll periodically find things of use. There are bombs, keys, and coins that can all be used to damage enemies or access new areas and powerful upgrades. There are also other items you can pick up – Tarot cards that have various positive or negative effects,  Isaac’s mother’s pharmaceutical pills, and rechargeable weapons like super-bombs, a teleporter, or your mother’s bra, which you can use to smother your enemies.

And there are also the powerful, permanent upgrades that Isaac can stumble across – he may pick up an onion that makes him cry even more than before, meaning he’ll be able to attack enemies faster, or he may find an ever-beating heart he can graft onto himself for extra health. Or a ouija board, a pair of high heels, a clothes hanger to stick through his head, a battery, a crown of thorns, growth hormones, a broken mirror, or even a miner’s hat. All these are distributed randomly throughout the map, and all have various effects on Isaac; some as simple as increasing his damage, and some as strange as bestowing Isaac with a loyal chunk of floating meat that will attack his enemies. You’ll only encounter a small number of these in any one playthrough, and since they’re placed randomly you’ll never know exactly what you’re going to come across.

Once you start a new game after dying for the first time you’ll notice that the world is completely different each time you play. The maps and the distribution of enemies and items are all randomly generated at the start of a new game, and even the bosses you fight at the end of each floor is chosen randomly from a large list. And it’s an interesting variation as well, not simply randomly generated environments for their own sake; the layout of the rooms, the placement of different types of enemies, and the upgrades you find all change the way the game plays to a large extent. So no two games of The Binding of Isaac are the same, and nor are two versions of Isaac. In one of your games you may come to develop an Isaac with a miner’s hat, a pet bat, laser eyes, and a large pot-belly. But when you play the game again your Isaac might with time come to have a third eye grafted onto his head, as well as a handy ladder for crossing gaps, tears of blood, and a pet dead cat. Each upgrade visually changes Isaac, so by the end of the game you’ll most likely be controlling some kind of grotesque, shivering abomination. And as well as finding or winning these various upgrades you may also be lucky/unlucky enough to stumble upon the devil, who’ll be happy to grant you various ungodly powers in exchange for a part of your humanity.

There’s a constant sense of uncovering new and surprising things throughout the game – you never know what the next room is going to be like, and there are so many different items and upgrades to find that you could play all the way through tens of times without seeing everything. The many types of enemies are all varied and, with a few minor exceptions, interesting to engage with. All, however, are gross, wretched things. Some, especially the most powerful, are simply monsters, but many seem to be abortive versions of Isaac. You start to wonder where all these monsters,so many bloated and crippled children, came from. The various enemies will all respond to Isaac differently; some will flee from him, and must be murdered in cold blood in order to progress, but some will attack; running at you angrily, or hobbling impotently towards you on broken and misshapen limbs.

All are disturbing in their own way – from the crying, defenceless twins of Isaac to the rotting, silent shopkeeper who is hanged open-mouthed by a rope around his neck. The art-style of The Binding of Isaac is very cartoony, as I’ve said, and it’s really quite nice to look at, but it’s especially impressive because of how it clashes so horribly and so deliberately with the themes and the content of the game itself. From the strange retelling of the Binding of Isaac biblical story, to the nightmarish enemies, to the pulsating flesh-walls of the final post-ending level (set inappropriately enough inside Isaac’s mother’s womb). Some of the things I encountered genuinely made me wince a little, and it’s clear that the game revels in making you feel uncomfortable.

It is very hard. But although a lot of the time you’ll die because there just weren’t enough health-restoring items to be found, it doesn’t feel unfair. It demonstrably is unfair, since on some run-throughs you’ll be far more ill-equipped than on others through no fault of your own. But it doesn’t feel unfair, because it’s so quick to get you on your feet once you fail, and so generous with imaginative and challenging possibilities.

It’s also certainly intriguing to play a game as bleak and dark as The Binding of Isaac. Very few games choose to go anywhere near this level of depravity (though I should reiterate that you won’t see anything visually shocking – it’s the ideas that it puts into your head that are sometimes worrying). It might make you uncomfortable at times, often it seems to want to do that more than anything else, but at heart it’s a hugely enjoyable game that is clever, imaginative, and challenging. Perhaps it doesn’t do all that it can with the themes it take on, but what it does do it does well. Very well, in fact.

When you get down to it, however, The Binding of Isaac is mostly trying to be a compelling, fun experience, and so the disturbing nature nature of Isaac and his journey may seem to be merely window-dressing. But Isaac’s story, and the grotesque nature of his experiences, feed into the feeling of playing the game – you’ll constantly feel  under threat and lacking control. And this is a game whose fiction and mechanics are all about defencelessness, as well as dealing with a violent and depraved world, and the physical and emotional trauma that entails. Like Isaac you’re thrown into a scary, imposing situation that you have to come to understand in order to survive,  and it’s a situation that’s as challenging as it is unpredictable. And even if Isaac survives all this it’s clear that he won’t experience a happy ending. He’s far too scarred and damaged for that, and this shows not only through the narrative, but through the mechanics themselves: the  only way for Isaac to grow stronger is to mutilate himself . The upgrades you find are rarely a nice hat or a handy pair of x-ray glasses. So often picking up a useful upgrade will also cause lumps to grow on Isaac’s body, brand him with the mark of the devil, or leave him lobotomised, drooling and grinning emptily. All this seems strange to say when I consider how fun the game is, and there is certainly an oddness there. The Binding of Isaac is clearly reaching towards strong, emotive places, but this seems to conflict somewhat with its enjoyable, light-hearted mechanics of roaming around, fighting, and growing stronger. I would have been interested in seeing just how far this game could have gone in abandoning standardised videogame tropes, while also developing the disturbing themes around which it orbits. As it is there is a dissonance within the game. However, it certainly succeeds at what it is trying to do, and despite this dissonance The Binding of Isaac is a powerful effort, as wonderfully disturbing as it is effortlessly compelling.

The Binding of Isaac is out now for PC, Mac, and Linux. It’s very cheap, around £5, and it’ll probably run on your crappy laptop.