Listed in no particular order, these are some video games that I think could be novelized well.

Square’s Xenogears for the Playstation 1.
This JRPG (Japanese Role Playing Game) is two disks or 100+ hours long. It’s this long because it has an incredibly detailed plot that slowly unfolds through an epic journey that is full of political maneuvering, secret societies, flashbacks, lost memories of past lives, and various scientific meddlings – from mutations to super-weapons.

I think the complexities of the various plotlines and their connections to the overarching story would be best suited to a Game of Thrones style Epic Fantasy novel, with each chapter/section being told from the third-person view of a specific character. As the characters meet up, the different pieces of the puzzle would come together and the story would become more cohesive in a way that would mirror the gradual unraveling of the mystery that binds everything together.

Square’s Final Fantasy VI for the Super Nintendo/Playstation 1.
Another JRPG – this one takes on a more Hero’s Journey feel as it follows the growth of the main character. It’s a 60+ hour game, but alas, many of those hours are spent in combat as the player navigates the “Random Battle” system or grinds to level up characters. Because of this, it’s easy to lose track of the actual story.

So, this one might actually be better suited for novel form because it would give a chance for greater character development (something that’s hard to do when you have 14 playable characters) and there wouldn’t be giant breaks from the plot while you battle things, making it easier to follow the chain of events.

Square Soft’s Secret of Evermore for the Super Nintendo.
Yup, an RPG again. This one is very quirky and involves evil robot butlers, a sabotaged time machine/holo-deck type invention, and an average small-town boy and his dog. It couldn’t be adapted as a “serious” novel, I don’t think. But if it was approached in the same semi-humorous manner of Good Omens or in the surreal style of Neverwhere, I think it could work quite well. Obviously, I’m leaning towards Neil Gaiman as the prospective author, because he’d be able to capture the fun quirkiness of the whole thing, while still preserving that creepy undertone that characterizes so much of the game.

Valve Coorporation’s Portal Games for the Xbox360. 
So, not an RPG, yay!!! The Portal games are puzzle/platform games with amazingly brilliant dialogue. As it is, given length and game design, both Portal games would have to go into one book in order for it to work, since the original game and its sequel make one complete story arc.

The story itself is outside my usual High Fantasy genre and I think it would work best as an action/suspense style, almost-psychological horror novel in a sci-fi setting. The deadpan humor would keep it from being truly horrific, but it would still translate as creepy, I think. But seriously, come on – newly re-awakened human test subject trying to survive and escape a hidden test facility run by a sadistic, sociopathic robot? Would be a cool book!

Supergiant Games’ Bastion for Xbox360 and PC. 
The way that the narrative in this game is set up would make it impossible for a direct translation from game to book. However, the story is compelling and keeps the gamer wanting more. Absolutely a Post-Apocalyptic novel, it has a Hero’s Journey feel to it that would make it epic in scope. And it has the potential for a wonderfully Inception-esque ending! It stands out in the Post-Apocalyptic genre because of its colorful scenery and light-hearted artwork. If that atmosphere could be captured in novel form, it would be a very interesting take on the whole thing.