The new characters steal the show in Invisible, Inc: Contingency Plan

Contingency Plan is the new DLC pack for Invisible, Inc, a turn-based stealth affair that is swiftly becoming my game of the year. Klei Entertainment - an outfit that is swiftly becoming my developer of the decade - clearly knows what it's doing here. Contingency Plan contains new enemies and new abilities, and its big ticket item is probably a unique mission that extends the campaign - and swiftly cut a rather promising team to ribbons on my first playthrough. What's really brilliant about Contingency Plan, however, is the four new playable characters it offers. They've completely changed the way I approach things. They've completely changed the whole game for me.

I now see that I was getting into a bit of a rut. A pleasant rut, but a rut nonetheless. Invisible, Inc is a game about sneaking into procedurally-generated corporate HQs in a vividly nasty near-future, pulling off some industrial espionage and then pegging it to the exit. But you have to find the exit before you can peg it, which means that each mission is fundamentally about exploration. This, in turn, meant that in the original game, I swiftly became addicted to leading Internationale into battle, since, in addition to a gloriously-antennaed set of headphones, she came with a special power that allowed her to reveal computery objects through walls and hack them from a distance. Inevitably, this ensured that I took to using her as a kind of Wi-Fi slug, smooshing her around the edges of every room we moved through, since she allowed me a limited view of the wider landscape.

This still works in Contingency Plan, of course, but now Internationale has some competition.

Take Olivia. Like everyone else in Invisible, Inc's universe, Olivia comes with a deliriously pleasing character portrait, realised in a shimmering low-poly style that accentuates elegantly gaunt facial features and pixel-perfect deployment of the side-eye. Now that I think of it, Olivia actually resembles a steely university professor from about twenty years ago - she once told me that her anger was only matched by her contempt - and, rather fittingly, she's also double-dangerous and appealingly short on patience. Olivia's special skill is that she converts KO points into the PWR currency you spend when hacking around in the mainframe. I scanned that fact rather quickly when initially selecting her for my team, and I only came to truly understand it halfway through a tricky mission in which there were suddenly a lot of enemy robots nearby and in need of hacking. I was low on PWR - I always seem to be low on PWR - but Olivia had already clubbed and pinned a patrolling guard. All I needed to do was ensure that she reclubbed him on a regular basis, and - hooray! - my PWR problems were a thing of the past. Olivia's a melee specialist, then, but she's also a resource plant. What a find!

I like to combine Olivia with Draco, who I'm starting to see as Invisible, Inc's hard mode. This probably isn't true if you're a truly skilful and tactical player, but so far it's been the case for me as I fumble along, surviving each encounter by the slimmest of margins. Draco's gimmick is that you can't buy him skill upgrades. Instead, scanning KO'd guards will provide a one-shot bonus of some kind, while scanning dead guards will add a permanent improvement.

This is dangerous stuff, and it's typically beautiful in its balancing. If you play well with Draco, you can turn him into a powerhouse without spending a cent on him, meaning that bringing Draco into battle will actually speed everyone else's skill evolution as your money goes further. The trade-off, though, is that killing guards in Invisible, Inc's world is generally an absolutely terrible idea. Killing guards raises the security level, and since this game hinges on the idea that the more you dawdle, the more dangerous everything becomes, Draco can be a carpool lane to catastrophe. Great rewards but at an insane price: this is character balance.

Needless to say, Olivia and Draco go together rather brilliantly, the first clubbing people for PWR boosts while the second despatches them permanently to become a more effective operative. They're joined, though, by two more characters who I'm still getting to grips with. Rush comes with a hot pink bob and a perk that makes her more dangerous when sprinting, while Derek can teleport to a deployable transport beacon. Teleporting! Both represent traversal options so exotic and far removed from the halting, stuttering way that I play that I haven't been able to grind anything but tragedies out of them so far. That's not a slight, mind: it's probably an endorsement. Both promise to mix the game up in ways that I have yet been unable to imagine.

The very best thing about this motley of hard-nuts and short fuses, though, is that it's brought me back to Invisible, Inc after all this time. Back to a wonderfully compact game that uses systems and procedural maps to create the kind of tension and last-minute escapes that scripting could never hope to reach. As the big games get bigger - and frequently more ragged with it - Klei is here to show that there is a glinting pleasure to be found in economy.