Blizzard have told us that they would consider removing units for StarCraft 2's second expansion, Legacy of the Void. Speaking at a recent press event, StarCraft 2 lead producer Chris Sigaty told us that "it would be a mistake for us to just put out units to put out units," adding "will we do that again for Legacy of the Void? I don't know. It may be that putting out new units for Legacy of the Void is a mistake."

Sigaty was speaking to us at the first press showing of Heart of the Swarm, for which Blizzard plan to add new units. We asked Sigaty about Blizzard's golden rule for StarCraft 2 which says that for every unit introduced, something has to go. How would Blizzard manage that with two expansions?

"The golden rule is there," says Sigaty, "there's only so much more we can put in. We're already at the Brood War expansion level number of units right now, so there might be a little bit of wiggle room right there, but not much more.

"It may be that find and replace becomes a reality for a race, or all the races… our intention for Heart of the Swarm right now is to add, but we could take it away."

Is it possible that we could see well known multiplayer units disappearing as well? Sigaty remains tight-lipped. "Multiplayer is something we're not locked down on, and we're just exploring," he says.

For the first details on the first StarCraft 2 expansion, check out our Heart of the Swarm preview , and the first teaser trailer .