http://www.computerandvideogames.com/interviews/interviews_story.php?id=134751
Exert from article
What particular challenges does penning a plot for an episode throw up, as opposed to penning the plot for a full sequel?
Robin Walker: It's the difference between running a marathon and running laps in a relay race. We set things into motion knowing that we're not going to resolve them immediately, so we want to make sure they have an actual destination and can stand on their own. Instead of wrapping everything up in one bundle, we have to stay several leaps ahead of ourselves. Each episode must both be self-contained and set up plotlines to be resolved or explored in the subsequent episodes. The nice thing for us about working episodically is that during the final polishing stages it's possible to see the whole story very clearly and make smart decisions about which elements need further development. This is much more difficult in a more traditional (non-episodic) game.
Should we really trust the Vortigaunts, because we have a sneaking suspicion they're hatching their own plan to take over Earth...?
Robin Walker: The Vortigaunts will play a very important role in what happens in later episodes.
Enjoy,

Exert from article
What particular challenges does penning a plot for an episode throw up, as opposed to penning the plot for a full sequel?
Robin Walker: It's the difference between running a marathon and running laps in a relay race. We set things into motion knowing that we're not going to resolve them immediately, so we want to make sure they have an actual destination and can stand on their own. Instead of wrapping everything up in one bundle, we have to stay several leaps ahead of ourselves. Each episode must both be self-contained and set up plotlines to be resolved or explored in the subsequent episodes. The nice thing for us about working episodically is that during the final polishing stages it's possible to see the whole story very clearly and make smart decisions about which elements need further development. This is much more difficult in a more traditional (non-episodic) game.
Should we really trust the Vortigaunts, because we have a sneaking suspicion they're hatching their own plan to take over Earth...?
Robin Walker: The Vortigaunts will play a very important role in what happens in later episodes.
Enjoy,
