I've done a lot of thinking about Portal 2, and why its structure appeals to me so much.
Also yeah, spoilers spoilers SPOILERS abound. For Portal 2, for Oddworld shit, and.. stuff.
The structure of the original Portal was simple. The protagonist wakes up in the Aperture Science Enrichment Center and must exit. Portal was an exodus.
The structure for Portal 2 is a little bit more complex. Upon first glance, it appears to be the same as the original, with the protagonist waking up in the Aperture Science Enrichment Center again and trying to escape. But no. The story is so much more complex than that.
First, we have Wheatley trying to break Chell (the protagonist) out, taking her along and looking for the exit. The game starts off giving us the expectation that the game will follow a similar exodus structure to the original. Then the protagonists accidentally wake antagonist GLaDOS up. Wheatley is taken behind-the-scenes, and Chell is placed back into testing. As the testing continues, Wheatley meets up with Chell and explains that he wants to return to GLaDOS' chambers to take her out somehow.
At this point, the player subconsciously figures out that the focus of the story is no longer on exiting the facility, but rather on returning to GLaDOS. This is most apparent to veterans who have played the original, as they would undoubtedly acknowledge that, in the end, they are going to go back and fight the big boss like in the previous game.
Then things change up.
The protagonists break out of a test chamber and make it to the antagonist's lair. What happens? Well, I won't explain the specifics, but Chell is sent miles underground. She has left the industrial facility and is now lost in the more.. natural areas. Though in this case, the natural areas are still very industrial, but bare with me; I'm setting it up for a comparison later on. In these more natural areas, she will brave individual "courses" where she will master new abilities.
At this point in the game, the player's focus is a little vague. But as Chell progresses through the subterranean tests, she meets up with a person whose name I'm not sharing on here. There are spoilers in this post, but not that many. By this point, the character announces that the protagonists need to head upwards to stop another character from destroying the facility. We'll just call that one the antagonist.
So the player realizes that the focus is now definitely on returning to the industrial facility. I can stop telling the story of Portal 2 here, as this should be enough for my analysis.
As Portal was an exodus, Portal 2 is, in many ways, an odyssey. As you can probably assume from my previous paragraphs, an exodus focuses on exiting (on a rather epic scale, I'd suppose) while an odyssey focuses on returning.
Now, as to the underlined words. What prompted me to analyze the Portals and discover their ex/od structures was a realization I had mid-second playthrough of Portal 2. I was in the natural areas. I then realized,
"Hey. There's another game out there, a game I grew up with, that told the story of a slave in an industrial factory of sorts. The slave escapes, only to wind up in some temples out in.. nature and stuff. In the temples, he masters new elements, returns to the industrial factory, and gains redemption or some shit.
"That game was Oddworld: Abe's Oddysee. Spelling intentional."
See, I grew up with many things. Oddworld was one of them. So Portal 2's structure reminded me subconsciously of Abe's Oddysee, and that touched my heart. It was then after I considered that Abe's Oddysee actually does tell the story of an odyssey that I started to consider the original's exodus structure, and how fucking fitting the contrast between the two is.
...so yeah, I'm done. Sorry. I lost my train of thought. I'm done now.