StarCraft 2's Nova Covert Ops is the closest we'll get to a piece of vapourware royalty

Where next for StarCraft 2? Back to an ancient promise, I think. Back to StarCraft: Ghost, the stealth-action console title that never was. Because how to take what's great about StarCraft and shift genres like that? Maybe the solution is simple: reverse it. Bring the Ghost to StarCraft itself. Build a suite of RTS missions around the cancelled game's heroine, the sneaky psychic operator Nova.

I like this idea. StarCraft 2's single-player campaign may never be where the game's true greatness lies, but across three releases, Blizzard managed to turn the story mode into a carnival of gimmickry - a place where soap opera plotlines unfolded while OP units marched out onto the battlefield, a place where an RTS could mean zombies, lava tides and a massive gun that can drill through mountains. Now that StarCraft 2's three acts are done, here comes Nova Covert Ops, three episodes of three missions each, with a new lead and a new storyline. The first batch has just landed.

And Nova's a spy, right, so the first mission, which sees her escaping a strange facility where her memory may have been meddled with, offers the opportunity to see Blizzard having a go at stealth. I know, right. This means avoiding vision cones and snapping necks until you get your hands on a rifle. Then, because it's Blizzard, it also means getting grenades right after the rifle. Stealth with high explosives! It works, in a delightfully zany way: enemies scattered in the air every time you land a direct hit, rooms breaking down into clumps of danger which you pick a path through as neatly as possible. There's a squad to reunite, and then a dash through the streets, dodging oncoming traffic and tangling with a boss. The staging is a bit rickety for this last part, but it's filled with heart, I think, and it's a clear indicator that the novelty of single-player design isn't going to be disappearing any time soon.

Neither is the Blizzard approach to storytelling. As a succession of men in ridiculous outfits inform Nova, there's a new threat to the Dominion. A splinter group called the Defenders of Man is trying to move in on their territory, and the Zerg are on the march again too. Nova's been pegged as a traitor, but before there's time to worry about any of that, the second mission swoops in and we're back to more traditional RTS territory for a while, with Nova and her stock of grenades tasked with protecting a Dominion outpost on the corner of a small, frosty map while wave after wave of Zerg try to rush it.

Nova's a decent hero unit for a mission like this, but you can more or less ignore her special powers and focus on business as usual if you fancy, which means cranking out Reapers and ducking around nearby canyons for top-ups of Vespene gas. It's a reminder that some of the series' greatest drama comes in small packages: there's a limited area to control, but with paths strung throughout it, the Zerg can still give you a run around.

The third mission's my favourite so far: deep in the thick of it on a Terran world that's long been overrun by the Zerg. Before setting off you can tinker with your gear a bit, swapping out weapons for Nova and giving units upgrades. Then you're pushing the Zerg back while you garrison a selection of nearby buildings. It's a relentless fight with bottlenecks built in, and it cements the sense of intricate fun Blizzard's bringing to this expansion.

Over time, this might become a really decent mini-campaign, in other words. Nova's an interesting lead when it comes to the tools at her disposal, and Blizzard's all-in with the nutty storytelling and the random flights of gimmickry. It feels a bit odd for StarCraft 2 to be getting this single-player injection after the main three games in the series have come and gone, but I'm enjoying it so far and I'm interested to see what comes next.