Idols Of Ash review - a terrific spelunking horror game that makes you choose between a rock and a giant centipede

When I think of Idols of Ash, I think of seven sounds, listed here in order of deepening dreadfulness. The first and nicest sound is the clink of my silvery grapple sinking its hook, interrupting the rush of air past my ears as I fall. That's the second, less nice sound. The third sound is a distant, tectonic groaning, disconsolate and wakeful: it could be the wind again, pushing through some unaccountably musical lungful of stone. Yeah, I'm sure that's all it is.

The fourth sound is definitely not the wind: a squeaky, squidgy rumination, like the cooing of idle pigeons. You hear that cooing and you start running, because it generally precedes the fifth sound, the stiletto rattle of chitinous feet. When the legs are close, there's the sixth sound, a rasping, gaping hiss, and it's time to yeet yourself into the chasm while hurling your grapple towards the nearest jutting surface. With any luck, you will not then hear the seventh sound: the thud of your hook bouncing off the rock.

Idols of Ash casts you as a bereaved spelunker who is trying to reach the bottom of a sunken, sandy megastructure, while avoiding the attentions of an unpredictably spawning giant centipede. You may have already encountered the centipede on social media. It's catnip for the reaction-farmers, a segmented, scurrying hellbeast that rivets the eye and frenzies the bladder. You spy that thing zig-zagging around a cavern roof and all thought of route-planning evaporates, as you resort to the ultimate sprint button: gravity. Your character's health bar can handle the odd nip or plummet, but you have no means of defending yourself.

Still, the centipede is just the supporting act. By dint of how it hurries you along and also, how ingeniously it navigates the contours - tick tick tick - the Creature sharpens your appreciation for the megastructure itself: a kilometre's depth of hanging archways, inverted towers, vertical pipes with carefully spaced protrusions, sloping slabs, and ashen kilns ringed by spectral vegetation. Marked from afar by gouts of green light, the kilns are both waypoints and checkpoints. Breathe in the ash and it will "remember you", teasing out a few sentences of your character's past.

The world is a cancellous abstraction, like something out of NaissancE, but also a convincingly built and deteriorating place, where unrecognisable planes gather into what could almost be streets. I wonder how much of this ambient indecision is inherent to any catacomb or mausoleum, architectures built to accommodate, or entrap entities that no longer need any earthly dwelling. I'm similarly uncertain about the little limbless statues you find, huddled around hovering flames that restore your health. The statues look humanoid when upright, but they're worryingly grublike when teetered over. Perhaps they are really the Creature's eggs. Perhaps this isn't a tomb, but simply a nest, with human vestiges grown to lure the unwary wanderer seeking catharsis underground.

Image credit: Leafy Games

The story is told by way of those kiln memories and a couple of cutscenes. It's a brief tale of loss and despair – the first run takes maybe an hour, and you could fit all the text on one page – with a slightly cumbersome exposition dump at the end. I otherwise admire the writing's sparseness and pungency, the repeated line about the ash "remembering you" being a wonderfully predatory framing that reminds me of the Shalebridge Cradle. Still, I think I'd have preferred Idols of Ash to be devoid of even these sparing bits of backstory. The larval stalagmites and ash piles don't need any 'grounding'. Coleridge's much-abused exhortation to suspend disbelief takes on new resonance when you're dangling from a rope with a nightmare arthropod at the other end.

Complete the game, and you'll belatedly realise that Idols of Ash is designed for speedrunners. The grappling physics are both intuitive and rewarding to experiment with. You start by learning the length of the rope, indicated on the HUD, and mastering the speed and trajectory of the hook's flight. Sometimes, the distance between ledges is exactly the length of the rope, but the gaps increase as you descend, and some of the 'routes' prove to be dead ends – extremely unpleasant, when the Creature is close behind. Then you learn to use the hook while falling. You also learn to use it on the flat, leaping and grappling for a speed boost. With practice, you can be a passable Spider-Man, swooping from arch to arch. Except that Spider-Man is not a fun parallel, here. Tick tick tick.

There's a harder mode to unlock, in which the Creature is more aggressive and tenacious. Better yet, there are a couple more maps. Best of all, there are inverted maps that invest the terrain you insolently tumbled through with new deviousness. If you survive these and are up for more, the logical next port of call is the rather more technical White Knuckle. Or if you don't want to feel all spooked and depressed while spelunking, why not take a swing at lovely freebie Grimhook.