Mass Effect 1 & 2, BioShock, the Half Life series and Modern Warfare 1 & 2 all struck a cord with me, but I think the game that effected me the most is shockingly Perfect Dark Zero. Now before everyone starts screaming at me "that game sucks", "Microsoft ruined the series" etc., the reason is effected me so greatly is because it inspired me to start writing my own books. I already know what you're thinking; "Soren, that gamed sucked and it's story was a piece of shit!" Yeah, I admit that the game isn't the greatest out there and the story isn't all that much either, but there were two huge things that really got to me.
The first was Miss Joanna Dark herself. To me, she's pretty much the greatest female protagonist out there and she's many things I've always wanted to be but could never become. The second was the year it was set in. I didn't (and still don't) think 2020 was far enough in the future to have all that fun junk they have. So, with the coolest heroine and a 'right' future date in mind, I set to write up my own books.
Currently I have two finished & unpublished books written up that were inspired by PDZ, and a third that I've started work on.