Blizzard has made it clear that StarCraft II will be released in 3 different episodes, each starring one of the game's warring factions. The first episode of the trio, StarCraft II: Wings of Liberty, will be released this year and will host the Terrans single player campaign.
Blizzard decided to give Protoss fans a little gift in the form a 'mini-campaign' starring the sons of Aiur, where they will be able to play as Protoss in single player.
"This part of the campaign mode is of course way shorter than the Terran part, but it is very fun to have a very different play style to add even more variety to the game. I am sure every Protoss fan will love this part of the Campaign!" Blizzard's Stefanie Gwinner wrote on the game's official forums.
"That being said, the Protoss mini-campaign will not prepare you for the multiplayer as Protoss, you won't be using all units or getting to know buildings and upgrades. In general, even for Terran, it is not the objective of the single player to show how to play the game effectively, it is to tell a story and do a lot of fun things, that would not be possible in multiplayer."
"The Challenges, mini-missions, that ask you to complete a very specific task, are more suited to give players the opportunity to learn how to use the units and how to play the game."
Blizzard's latest RTS (Real Time Strategy) game, WarCraft III, has seen a similar mini-campaign which acted as the game's prologue where players played as Orcs for 2 or 3 missions before starting the humans campaign. Of course, back then the Orcs had their own "complete" campaign later in the game.