Personally, I love this question because it reveals if a prospective candidate has a plan at all or is just drifting from job to job as so many are wont to do. There's nothing wrong per se with people who drift along the currents, it's just that those with a plan (or at least a desire to move in a particular direction) are generally much more interesting people. Plus, they are almost always inherently more predictable, which is always a benefit for employers.

Having a desire to move forward helps everyone. It helps you measure your progress, and it gives the company a plan to help you get there.

Of course, it does depend on you knowing what you want. Most people tend to know what they don't want, but not necessarily what they do want, which is a problem -- particularly if you express that in an interview. Interviewers would rather have a list of things you want to attain rather than things you don't.

One optimal answer is, "Still working for you making games," but it smacks of sucking up, so I'd recommend saying something a little more generic: "Still looking for a challenge and putting in that extra effort to make great games."

The best response I've ever heard to that question was, "I want your job!" and the individual who said it to me indeed has my old job! But be wary of sounding confrontational.