Worthwhile books with related game series?

You always hear about movies/tv/etc being adapted to video games or occasionally vice versa, usually with sub-par results. But what about novel series? Any reads that you'd recommend which were also made into video games? What about stuff that would make a fun game? Be sure to say if you are listing #existing book-to-game series or #proposed ones. ;-)

I'll start it off with these:

Existing

These all have been made into video games.

• The Witcher series by Andrzej Sapkowski - I've only played the first 2 and I was one of the few who liked the controls in the first game more than the controls in the 2nd. The books, I will admit were not my favorite, but I know if I didn't mention them then every other comment will be about them. Too much contempt and too slow paced for me. Game takes place in same world, has same characters, but follows its own story

• Harry Potter - Read and enjoyed the books. Never played the games, lego or otherwise.

• The Riftwar Saga by Raymond E Feist - The game "Betrayal at Krondor" (note that the bundled Antara game is not related to this book series whatsoever) takes place in the same world, has characters from the books, dialog and chapter text feels like it comes from books, game has it's own story that was later made into a secondary novel series. This was one of my favorite games growing up and I loved the books too. Looking back on the books, some of that is definitely nostalgia; the books were decent but definitely not top-notch by today's standards, the series was written in the 80s and especially the first two have the feel of a new author. I still would recommend them, just not as strongly as something like Harry Potter or The Dresden Files.

Proposed

AFAIK, these only exist as books right now, but would probably make fun video games.

• The Dresden Files by Jim Butcher would make a great action/rpg or action/mystery setting.
• Stormlight Archives by Brandon Sanderson would make a great action/rpg setting. His Mistborn series would work really well too. I think Stormlight would have a slightly better time transitioning to video games but it's really so damn close that it's a toss-up.
• The Grimnoir Chronicles by Larry Correia would make a great shooter + super-powers game.
• Hard Luck Hank by Steven Campbell would make a great Monkey Island or Deponia type point-and-click adventure.
• The Gentleman Bastards by Scott Lynch might make a good setting for some kind of heist/elaborate confidence-trick game (less GTA; thinking something like a more like a mix of Sly Cooper, Ocean's Eleven, and Game of Thrones). Heads up that the first half or so of the first book is a bit dull but wait it out and you won't regret it.
• The Expeditionary Force by Craig Alanson might make do as a good backdrop for a sci-fi stealth game where you have to complete missions without revealing that you're human.
• The Posleen War series by John Ringo might make a decent space marine/mech-suit fighter game or even a decent sci-fi RTS. I will say I got bored of the books after the 2nd or 3rd one but the first book was pretty solid.
• Codex Alera also by Jim Butcher would probably make a pretty good Elder Scrolls type open-world fantasy rpg setting.
• Ender's Game by Orson Scott Card would make a pretty cool team battle game (like Gears of War/COD/etc/etc team deathmatch) BUT I think this would be pretty damn cool in VR. Apparently, someone else liked this idea too but dev was stopped. ::crosses fingers that it resurfaces someday::

EDIT: Btw, in case anyone is interested in avoiding spoilers:

• Been awhile since I read the Witcher books... I think the tv show and the books have roughly the same plot from what I could remember. IIRC, the games d their own thing so there's no really any danger of spoilers and either the books or TW1/TW2 games are safe to play first. I haven't gotten to TW3 yet, so I can't confirm but I believe it is also separate plot from the books.

• Betrayal at Krondor takes place after the events in the 4 Riftwar Saga but you don't really need to have read the books to enjoy the game. The events in the game take place in a second 4-book series called the Riftwar Legacy which does contain spoilers for the game.

• Haven't played the HP games, so I can't comment on those w/r/t spoilers. The movies follow the books pretty closely from what I remember so if you've seen the movies/read the books, I assume you're fine but not sure about spoilers if you start from the game.

• As mentioned below, Mass Effect you should start with the games as the books will have spoilers.

• Lords of the Rings. I only played one of them (War in the North I think) and it was a completely separate plot from the books/movies. I think some of the lego ones might follow the book/movie plots but am not sure. The MMO should be separate I think. If in doubt, read the books / watch the movies first and you should be good.