In a surprising announcement during BlizzCon, Blizzard revealed that StarCraft 2 will be released as a trilogy of titles, each focusing on one of the game's faction.
Blizzard executive VP of game design Rob Pardo explained that the development team's original plans for the game were too massive to be implemented in a single game, so they decided to split it into 3 separate titles: Terrans - Wings of Liberty, Zerg - Heart of the Swarm and Protoss - Legacy of the Void.
Just like their names suggest, each of the three titles will focus on one of StarCraft's factions. Each game will offer about 26 to 30 missions with branching storylines that end up in the same place. The games will take place alongside each other and multiplayer functionality will be in place for all three races from the start.
Pardo noted that the decision was necessary to maintain the quality of the product, the alternatives either being a long delay of the game, or a scaling back of the campaigns.