How's this for trouble? A while ago, I spawned in a room that didn't have any exits. My fate was limbo, if limbo even counts as a fate: eternal life amongst corporate pot plants, a hackable computer and four blank walls.

Invisible, Inc constructs its mazes procedurally, and back when the game was in alpha you'd very occasionally get to see a genuine procedural hiccup like this. It was kind of energising. Nothing makes you realise how much freedom of approach a smart tactical game grants you so much as a situation in which you suddenly can't do anything at all. Nothing makes you dream of the things you might normally try like a few minutes spent in a room without doors.

Last night, Klei's espionage adventure arrived on Steam Early Access. Bugs like my limbo room are gone as far as I can tell, but the promise of the game is more obvious than ever. Invisible, Inc is already an absolute delight, in fact, and it's a stealth game unlike any I've played in a while - tightly focused, genuinely tactical, and empoweringly disempowering. It removes options in order to make you creative. Violence is costly here, and it can be dangerously loud, too. Moving quickly means drawing attention to yourself. Instead - well, what do you feel like doing?

It's hard not to feel cornered, even in a fairly roomy map.

Klei's mastered stealth before with Mark of the Ninja, and Invisibility Inc feels like the perfect inversion of that sinewy masterpiece, ditching real-time panic for the creeping dread of turns, opting for a neat isometric grid rather than side-on platforming, and exchanging honorable ancient warriors for spindly film noir cynics in trenchcoats and cuban heels. What both games share, though, is an ability to make sneaking past a foe every bit as satisfying as action games make plugging one in the skull. They make successful avoidance feel like an event.

And Invisible, Inc does this in part by constantly ramping up the danger. Every turn you spend as you try to reach each map's objective raises the alarm level, inching you closer and closer to the moment that a new security camera gets switched on or an additional guard begins their patrol. The environment, meanwhile, is filled not just with cover to hide behind but obstacles that block your line of sight. Your action points control how far you can move in a single turn, but it's these tangled layouts that really set the pulse, transforming each mission into a game of short, breathless hops from one vantage point to the next.

You can tell it works, because Invisible, Inc's so thrifty in the way it creates its big moments. The set-pieces here are corners for the most part - corners and doors. Shuffle up close and then chance a quick peek at what lies beyond: sometimes it's an empty stretch of hall and a few extra seconds of relative calm. Sometimes it's a bunch of heavies and hi-tech equipment.

Incognita mode allows you plan ahead - a little.

Heavies need to be lured out of the way and either dodged or clubbed - and clubbing always feels a bit like failure. As for the equipment, this sees you dipping into Incognita mode, which only reinforces the espionage theme. Incognita mode redraws the environment as a spidery wireframe and highlights any objects you can hack into. Cameras can be blinded, laser grids can be deactivated, safes can be opened to reveal their handy trinkets. All of this comes at a cost, though - a cost in PWR, which can be found in big chunks in scattered consoles if you can reach them, but otherwise will recharge, with agonising slowness, one unit per turn. Empoweringly disempowering, right? You can have something you'll find quite handy, but only if you take additional risks within the environment.

It's astonishing what all of this does to you as a player. Put aside the levelling system, the upgrades, a range of agents all stocked with their own strengths and weaknesses - Invisible, Inc makes you into a genuinely illicit presence within its cluttered maps. You're somewhere you shouldn't be, doing something that's probably a bit murky. You feel like a spy, and - the odd Splinter Cell or Deus Ex aside - that's still a bit of a rarity in a video game, where you're so often cast as a secret agent only to find out that it's just a flimsy layer of deep cover, and in reality all you are is the same old action-adventure goon with an over-developed crouch button. Clear that room, and then clear the next. Martini?

There's no room clearing in Invisible, Inc. There is, at best, room surviving, sometimes pulled off well enough to leave you with a feeling of rakish elegance. Survival stealth? I'll take that as a new genre. Especially if the games that follow are as thrilling in their restraint as this one is.