Either the original work the game was based on or an adaptation.

I just starting to read The Witcher series (currently finish "Sword of Destiny") and it is even better than the (excellent) games.

I also read Gabriel Knight: Sins of the Father, which is pretty much an accurate adaptation of the game, not surprise since it was written by Jane Jensen.

And of course my first encounter with my favorite book series, Discworld, was due to first playing the 1995 adventure game.

No, not that way around but I have played a game due to enjoying a book: Metro 2033.

Oh yes definitely. Dune 2 was my first RTS and one of the first games on my 386. I was fascinated by it right from the start and when I learned many years later that it was based on a book, I decided to go out and grab me a copy. It was amazing.

Now that you mention it, yes actually! Planescape: Torment made me so interested in the setting that I read Pages of Pain by Troy Denning, and I usually don't read much fantasy, least of all D&D stuff. Not such a great book, but my fanboyism made me overlook that, just because it was set in Sigil (even though the author took quite a few liberties with the setting).

Oh, and when I couldn't get into The Wolf Among Us, at some point I started reading the Fables comic 'books'. I don't remember if I did it because of the game or if it was accidental, but after getting into Fables, I gave The Wolf Among Us another chance and ended up loving it.

And I bought and read the Sam and Max Surfin' the Highway comic collection because I loved the first game.

I also tried reading a Witcher book because I thought it would make me enjoy the games more, but I wasn't too impressed.

Oh, right, I played Discworld because I was familiar with the books. But not the other way around.

I played Dune (the first one, not the RTS) long before I even knew there is a book. The game and that world really blew my tiny little mind, and started my fascination with the franchise. The scope of it and the ideas... it was my first contact with a space opera like that. And I was living through it, seeing it through the main characters eyes! The book is great (though in some ways also very flawed), and some of the sequels are damn good too, but the game was what made the greatest impression on me.

I read the witcher books, the 2 with short stories plus the 5 of the saga, before playing any witcher game, because I wanted to have a good understanding of what's going on in the story, the characters, the relationships, etc. I have witcher 1 and 2 and when I play them I'm sure I will enjoy them more now that I have read the books.

I suppose I would have come to Stalker eventually, given its persistant popping up in best scifi book lists and some friend's obsession with Tarkovsky. But I learnt to love the Zone in the game first, and sought its literary and cinema versions only later.

But more recently, I got intrigued by a couple of french muslim hip hop songs in Saints Row 3, because, given the general tone of gaming forums, I found lyrics like "everyday a muslim" or "i sing for those who don't eat ham" a little daring to include in your GTA-clone. But again, it's Saints Row. It's not very good at conforming to expectations.

So I checked out the singers (I'm vaguely anti-religious, and hip-hop is not my thing at all, but I was a tad wtf), and realised they were pretty cool guys, openly anti-islamist and anti-islamophobia. I also noticed that the lead singer had co-authored a book with Pascal Boniface, the famous french political scientist. It's a discussion book (titled as the song featured in SR3), confronting the insights and experiences of this "street-level" singer and of this geopolitical analyst's perspectives. Hip hop author-entertainer, and founder-director of geostrategy institute, discussing on equal footing, with mutual respect and understanding. And being on the same wavelength. It's a cool read.

Discovered through Saints Row. So, yay Saints Row.

(I like Saints Row.)

Well, a short story.

I Have No Mouth and I Must Scream

Well, you would have to read that one, it's not like he can tell you the story...
I read a samaritans pamphlet after playing dark souls for a few minutes.

Bram Stocker's Dracula on Genesis/Mega-Drive, made me get the book.

Mary Shelley's Frankenstein, on Snes, also.

Those were the days. In modern nights, i finally got myself a bunch of Vampire the Masquerade books after Bloodlines and the Witcher collection (there are some fan-made translations online for the books that are commercially available in Polish exclusively)... Although, i have yet to go through the latter's books, they are pending in my list.

Just don't expect anything quite as good as the "original series". It's not a bad book, but, as is often the case, it suffers from being a prequel to superior work.

The Witcher books, since I didn't know they even existed before I played the game (not a single one of my local bookstores had them on the shelves until a few months after the second game was released).

The small book in the Tales of Symphonia CE.

Aside from those, no.
There usually aren't books connected to the games I play (mangas which animes are based on which some games are bsaed on don't count).

My first time experiencing Faerûn and D&D was either through Baldur's Gate or Icewind Dale, since then I've read a bunch of the books around Drizzt and his acquaintances by R.A. Salvatore.

I also read a few of the Warcraft and Diablo books. I don't think I have anything from Starcraft yet... do I? I may have. (Many of my books are up in the attic as I haven't had the space for a good while to have them visible.)

I have read the Witcher short story bundled in the Enhanced Edition of that game, have not yet acquired the rest of the books though.

A bunch of stories were bundled with Torment: Tides of Numenera, but I have yet to read them. I suppose I should, since I am DM'ing a Numenera campaign and probably need a better feel for the world.

I read Starcraft, Warcraft and Diablo novels because I wanted to engulf myself more into the stories of those worlds.
I also read some of the Mass Effect novels and comic books because Mass Effect is just awesome. ^_^
I also started reading the Resident Evil novels (based on the game series), currently reading book five of the series (Nemesis) and it's pretty enjoyable.
Wanna get the Witcher series of novels but not before I finish the games, currently playing the second one.
Started reading the first Assassin creed novel, but it's not as enjoyable as I thought it might be.