It is probably pointless to try and get this discussion to work, but I'll try anyway.
Anybody who has read a few Video Game Novels, be they adaptions, prequels, sequels or spinoffs, should have noticed by now that they are very hit and miss.
Some can be pretty solid, or even very satisfying, but most fall flat on their faces sooner or later, with amateurish writing, plot inconsistencies, inaccurate depection of game lore or established characters or simply making no sense at all when read on their own.
And time and again I ask myself: WHY?! Why is it so god-damn difficult for authors to get the things right? Why feels the first chapter of a Splinter Cell novel so lackluster, like a very bad fanfiction retelling the game? Why are the Darksiders novel's action scenes feeling so... weak and sloppy? Why are the mass effect novels so full of lore errors and contradictions, despite representing similar events you can hear about in the games?
The list goes on and on.
There are also novels which can stand well on their own and have vision, like Deus Ex: Icarus Effect, which I have not read but heard very good things about from fellow reviewers. James Swallow was heavily involved in writing the Human Revolution game, and so he wrote a prequel novel to that, which now got a follow-up in the iOS game The Fall. His novel appears to be solid, doing its own thing while staying intertwined with things from the game.
Bioshock's Rapture novel is written in a very interesting way, using a writing style fitting of the post-world war 2 setting, creating a somehow believable stage for the creation of the city under the sea.
I'll propose a theory, I guess. One of the most frequent complaints about video game novels are inconsistencies with the game, the lore etc. I feel most of that could be avoided by a stronger bond between the game's writers and the author of the adaption. James Swallow did well with Deus Ex, John Shirley did well with Bioshock. The problem comes when the game receives a sequel which invalidates content from the first game(s), retcons things shown in the book, or when the books become too ambitious, trying to interpret things in a way the games never intended them to be interpreted.
Now, we can't do shit about retcons. They happen, and they happen often. Some are subtle, others are more obvious. Especially since novels get mostly written to accompany a new game, and a lot of things can change throughout game development, those things happen. However, I feel that this could be very well avoided if the novel author and the game's writer were to work together more effectively.
But what about the oftentimes shitty, amateurish writing? Why does Ubisoft put a huuuuge Tom Clancy's tag on their Splinter Cell novels, when Clancy hasn't done anything with the IP in forever, but letting his name outstrip the author, who the novel was outsourced to? Who do they think can they fool by drawing attention to Clancy, as a popular author, when the writing inside is so weak?
We assign editors to authors for a good reason, but either they don't care, don't do their jobs properly or don't have any clue of the material being written about either - but why don't they consult the actual writers of the games for help and/or assistance? I honestly don't get it.