Although I would myself label my sci fi choices as 'fan-boy love' it has not stopped me scrutinizing many of my own favourite series of story tie-ins for both movies/games and the books that expand on them.What I can probably do here is offer some books that will perhaps entice gamers (whom I would fall under in category) and those who just want a god story that just so happens to be linked to a game/movie.
First off would most certainly be the Gears of War series of books. I have read 3 of them now (The Slab, Aspho Fields, Jascinto's Remnant) and I must say Karen Traviss knows how to write a good science fiction that, although is fiction, feels firmly rooted to plausible thinking. I love stories such as Stargate where the science does not happen to be utter rubbish but possible theories. I am also partial to gritty stories of the Gears of War nature.
If you are not a fan of guns and soldiers in general for books, then this is probably one you should give a miss. On that note however, the story behind the Gears of War series, though iconically fictional (of course) is, I feel, plausible. The entire story takes place on the planet Sera and follows a group of protagonists that form a unit known as Delta Squad. Specifically two members of this team make the main story point. You have MArcus Fenix, a man who exhumes cold calculating thought that unleashes a torrent of hate when in combat, and his emotional counterpart Dominic Santiago, a man who becomes the guardian angel for Fenix.
Whenever Marcus would falter, Dom would be their to help him along. When Santiago would fall in despair at his losses, Fenix would drag him to safety. This brotherhood bond goes back to childhood, and though Marcus seems void of emotion, his feelings are far too intense for him to even attempt to deal with them.
The story itself follows the appearance of the Locust. A species that has swarmed upon Sera's surface from beneath. They live in tunnels, burrowing under cities and defenses to appear wherever they please, even using the man made sewer systems and metro tunnels to their advantage as they emerges out of Emergance holes to butcher those around them before stealing any technology at blinding speed. This species, as their name suggests, appears in swarms and cares little for their losses in a fight. Only to swarm again from another point without warning as the ground beneath the defenders collapses to reveal a horde of enemies that will grant no quarter. They are the thing of nightmares, and the Cog troops are kept awake at night by the smallest of tremors beneath their feet.
Without spoiling the stories themselves. I would definitely recommend this series to anyone who is a fan wanting to expand on their understanding of the story, or just want a dam good book to read. On that note I would perhaps recommand 1 of 2 that I have read to begin with. Aspho Fields explains much about Marcus Fenix and Dominic Santiago along with Anya, Marcus' love interest, and how they all tie together. After that book I would then move onto the Slab, which explains the time leading up to the first game and the crime Fenix committed that saw him stripped of his honors. Jascinto's Remnant takes place after the second game, and leads onto another book before the third and final installment.
Yes, I would recommend this series of books, as they are well written, tie perfectly into the games, and explain things that the games simply do not shed enough light on.
Once I look back on the other books I have read, perhaps I can add another recommendation. I only hope I did not drag on too long with this one...