It’s a fine balance, however. In addition to tapping something innately anthropomorphic in the cast, Kindregan needs to be sure he doesn’t stray into dangerous territory: “I definitely want to keep them alien, other, strange and different. But they still have to have that certain something that you can understand on a deep level.

“I have to make sure they don’t turn into humans wearing Zerg costumes.”

Two such characters are Izsha and Abathur. Izsha is an advisor; “the memory of Kerrigan as the Queen of Blades.” Her role is to tutor Kerrigan and, vicariously, the player on the nature of the Zerg and how they operate.

Abathur is a creature created by Kerrigan during her tenure as the undisputed ruler of the Zerg. His domain is the rapid evolution of Kerrigan’s Brood. For now, Abathur is a work in progress, which is to say, he probably errs on the side of being too “human.” All the same, Abathur serves a vital function in Heart of the Swarm.

Where Wings of Liberty tasked players with the accumulation of Zerg and Protoss research data, Heart of the Swarm asks the player as Kerrigan to seek out DNA. These evolutionary strands are invested in Zerg units in order to individualise them. Each unit can initially be upgraded one of three ways. Two options cost one point and another costs two points. Once three points in total have been invested, a meta-mutation can be chosen.

Zerglings, for example, can receive the “metabolic boost” upgrade to increase their speed and, or, “posthumous mitosis” for a 20 per cent chance to spawn two broodlings upon death. For two points Zerglings can be upgraded with “rapid genesis” to instantly spawn from larvae. Once three upgrade points have been chosen, Abathur can further evolve Zerglings to become either Raptors or Spawnlings. Raptors can leap over small units or onto massive units, whereas the Spawnling upgrade creates three Zerglings per larvae instead of two.

Abathur oversees the Evolution Chamber, one of two rooms aboard Kerrigan’s Zerg Leviathan. Rather than the four wings of the Hyperion battlecruiser that players will be familiar with from Wings of Liberty, only two rooms will be navigable aboard Kerrigan’s Leviathan. Instead, Kerrigan will “land” her Leviathan and each planetscape will be interactive much as they were in the latter Char missions in Wings of Liberty.

“We could’ve put you on a Zerg Leviathan and you’re sort of looking through a window at the world below, but it’d be so much more fun to get you on the surface and see,” explains Browder. “We did that in Wings, on the surface of Char, and that came to us towards the end of development: We put Char in [and were blown away], and thought, ‘That! That’s cool!’ right? So we did that set and were happy with it. The cinematics guys did a great job on it. And we thought, you know what? We want to do more of that. So we thought it’d be really cool to get you on the surface a lot more often.”

All of the above highlights the essential truth that Heart of the Swarm is a campaign addon. Beyond ongoing balance adjustments to StarCraft II’s multiplayer, very little or, more likely, nothing at all is being added to the game’s online component. And in spite of several discussions, Blizzard maintains that Heart of the Swarm was always going to be an expansion pack: “We have discussed [creating a full retail game],” says Browder. “It’s been discussed a few times but it’s never really moved away from our belief that [Heart of the Swarm is an addon].”

Heart of the Swarm, then, is narrative extension for those of us who need to know what happens to those characters we’ve invested in for more than a decade. It’s an evolution of the campaign footprint laid down by Wings of Liberty.

For our part, it can’t come soon enough.