It's based off the comic series, however the feeling of the movie is as if it is a video game.
I must say I enjoyed this movie a lot. I did get to watch it with 2 other people. One of which appreciates video games but isn't too integrated in them, and the other who couldn't care less for video games.
The fight one thought the movie was funny and enjoyed the general humor of the movie, but missed out on some of the neater subtle gaming references that I noticed. This person enjoyed it overall, however, not on the same level I enjoyed it.
The second person basically laughed at a few of the jokes, but overall didn't understand a vast majority of it. (See the Level 7 of the movie) Not necessarily hated it, but he did not enjoy it exactly.
Basically, I recommend this movie to any gaming nerd who is not completely sucked into all things FPS. I did, however, think some of the fights dragged the movie down a bit (generic ones like 1, 2, 3, and 4) but the endings to the fights (especially 3) were pretty funny.