Starcraft 2 Lead Designer Says Single Player Campaign Will Be Non Linear

Starcraft 2 lead designer Dan Browden said in a recent interview posted on Gamespy that Starcraft 2's single player campaign will have more depth, more branching paths and a lot more customisable options. He said:

Actually our campaigns will be structured in such a way that players can choose the path they take -- it's not a linear path. Our goal with StarCraft II's campaign is to give players the ability to make meaningful choices in the missions they take and the technologies they unlock, so as to customize their single-player experience. The choices you make can impact how different subplots unfold, or how soon you unlock certain units and technologies.

There will still be a single, overarching story we're trying to tell, so it's not as if there will be alternate endings to the primary plot line. But in certain subplots, players could affect the fate of specific characters or even worlds depending on the choices they make, while the ability to choose your technology upgrades lets you customize your army for your own playing style.

He also went on to hint out about a mission in the game:

"Tightly-scripted" may not be the right way to describe our philosophy as it relates to mission design in StarCraft II. Those of us who have played a lot of RTS campaigns have already played a bunch of the typical skirmish missions, or the commando-style missions where you navigate a hero character or two through a maze of enemies. We're not looking for StarCraft II to do 25 or 30 of those tried-and-true mission types.

We're doing our best to make sure our missions give players new and unique experiences, so we're viewing each mission as its own special mini-game. We don't want to give away too many surprises, but we can tell you that one of the missions will have you doing a series of train robberies. How that exactly plays out, you'll have to wait and see, but we're having a lot of fun putting these ideas into practice.

You can view the entire the write up of the entire QA over here:
http://pc.gamespy.com/pc/starcraft-2/940879p1.html