Silent Hill (2006)
Dir. Christophe Gans
As someone who's had minimal hands-on experience with the video game series upon which the film is based I can't offer any kind of proper game-to-film comparisons, but I can attempt a review for people who are new to the franchise, exploring the question of whether or not you need to already be a fan in order to appreciate what Christophe Gans delivered.
My short answer is no, I don't think you do. The film's strengths stand by themselves, and the failings in the story would be there either way.
One of the main differences between an existing fan's perspective and a newbie's would perhaps be the viewer's ability to give a backstory to some of the characters or creatures, and doing that may well come with its own kind of baggage or even add further complications to the plot.