Video Game vs. Book Sizes

I forget where this thought came from, but I started thinking about how the various ways video games are released (full releases, expansions, DLC, etc.) are akin to how books are categorized by length (short story, novella, novels, etc.).  Some of them are pretty obvious, a full video game release is just like a novel: it can both build a new world, create grand adventures for a set of characters (generally recurring characters in future sequels), and has multiple ups and downs as well as conflicts (albeit one main one).  Expansions are like novellas: the are generally smaller adventures with the same characters that have already been setup in the full game/novel, only have time for one real conflict, and don't really have time to do much world building.

DLC, on the other hand, seems to come in two forms.  It's either like reading the same book, but with a different font (the main content is no different, but there's at least one minor difference to how that content is experienced).  In DLC forms, this is the new weapon/armor/skin.  The other type of DLC is more like a short story.  It is generally a new small adventure for the characters you know and love in an already established universe.  I haven't seen any DLCs that are the other form, where it's a whole new set of characters used to build the world/universe further, except for maybe Bioshock 2's Minerva's Den.  I can partly understand this because where a short story only needs to reference things from the world it comes from, DLC has to use the same technology (and generally art assets) made to use the game it's a part of.  So the easiest way to make DLC is just to make more of the same thing as the original game.

What I haven't quite figured out is what (if any) equivalent there is to smaller full games (i.e. PSN/XBLA games).  Would this be like a magazine article?  Just sort of a small way to amuse yourself for a bit of time, but generally no real substance to it?  Obviously there are exceptions on both ends of this analogy.  Not sure what else it could be.  I'm also curious what the visual media (movies, television, etc.) compare to these.