You'd be surprised how often this question comes up, even if you aren't interviewing for a design position. Everyone wants a developer who has design sensibilities because it inevitably means she or he will be more involved and engaged in whatever is going on.

Knowing ahead of time how you might answer this question means you'll come off sounding like you've actually thought about a game in development terms. Game studios are looking for people who think as they play -- about what they're playing, how it's done, what could have been improved, and most importantly, what they can rip off.

One downside to adopting this mentality is that it becomes harder to enjoy a game for what it is, but that's an occupational hazard in all jobs.

Believe it or not, you can answer this question in an entirely positive way. However, if you decide instead to criticize a design or implementation decision in a game, be sure you have a solution to the problem too. It's not enough to moan about the final strider battle in Half-Life 2: Episode 2; you have to have an idea of how it could have been made more enjoyable, perhaps through easier car control, or not destroying all the supply stations so quickly.

If you decide to bash a game that the company where you're interviewing developed (and that takes courage; some companies will applaud you while others will diss you for not drinking the Kool-Aid), then ensure that what you're criticizing isn't something subjective but something that everyone has had a pop at. Be ready to back up the criticism with proof that it's an agreed-upon flaw, not just you being nit-picky.