What many people don't initially take into account is that writing for games is entirely different than writing for movies, and that's how many developers and companies approach it. Aliza pointed to a very interesting piece with Ira Glass where he talks about a great story through audio or video, and approaching it as storytelling. Glass is pretty knowledgeable on the subject, having hosted and contributed to This American Life on the radio for many years. If you aren't making the story and the experience integral to the gameplay, then you're just playing Tetris. Phoenix Wright is a great example of this ... the gameplay isn't groundbreaking or innovative, but the clever writing puts you directly in the story and in effect becomes the game.
According to the David Cook, the last thing you ever want to write into a game document is "And then the player does this ..." At that point, you've failed as a writer. What you have to do is write down what would make the player want to do whatever it is you're trying to have them do. You have to figure out how to get the story across by having the player "do" something. Not just get information from a talking head in a corner somewhere. Writing should inform game design, and game design should inspire writing. Too often game developers build a game, and then hire writers to come in and fill it out. This doesn't work because it doesn't drive the story at all, you're left with a bunch of talking heads. "Narrative designers".
Writing decisions are a lot like being an art director ... you dress the set, but don't have a lot of control. You want to be involved and care about the narrative. You have to teach the player what the meaningful objectives are. Think more about yourself as a designer, not just a "writer". If you're interested in trying to break into writing for games, the panel recommends first studying writing seriously, like creative writing, screenwriting, playwriting ... but to also realize that when writing for games, you turn a creative corner and take it a step further by being immersed in the game design.