The phone interview is often a screening interview, designed to ensure you're a real person, that you applied for the right job, and that you know enough to justify the costs of an interview. It looks like this is your first major interview.
There are the standard questions:
* Tell me about yourself. They want to know things related to the job, plus perhaps a few side interests that relate to being sociable at the job.
* What do you know about the company? Know what games they made recently, what projects have been announced to the media, and demographics of the company. For small companies figure out who the owners and founders are, because probably one or more will be in the interview and it is good to recognize them.
* Why do you want to work here? Don't joke about 'to earn a paycheck'. Why work at THIS company, instead of the one next door? Why THIS game studio, instead of another?
Have your friends and family drill you on these questions and every other standard question you can find. You don't want memorized answers, but you want to practice having good answers.
Since it is a game writing job, they'll ask all kinds of game related questions, particularly about the story lines of other games. They'll likely want to know about plot holes you've found, and what you thought about particular plots. Be careful that you keep statements positive when you are critiquing, you don't know the background of your interviewers and it can be a problem if you insult the work that they did; some people like the acknowledgement that you played what they created, and they saw the dark underbelly of the project and all the messy details, they want to know that you saw problems but want it presented in a positive light.
Since storytelling is part of your job you may be asked to create a story based on something, or expand on a story within a context they give you. Be prepared for that. If you have time to prepare, have friends and family help you with this, too.
Be prepared for the closing questions:
* What salary do you require? Salary negotiation is an enormous topic. There are many rules about it, such as not being the first to bring up a specific number, delaying salary talk until they're ready to make an offer, and how to make counter-offers that encourage things like signing bonuses, moving bonuses, or higher wages. Know how much the job should pay, and be careful that you don't bid against yourself by stating a number lower than what they're willing to pay. If you offer to work for less than they were planning they will generally take you up on the offer. Good salary negotiation can increase your wages by an enormous amount. I've seen skilled negotiators bump the initial offer by more than 50%. Salary is what you negotiate, not what you earn.
* When can you start?
And as was already explained, have questions. You are interviewing them just as much as they are interviewing you. Make sure you know exactly what the job is, what is expected, how you will be measured, when you will be measured, and who will be doing the measuring.
Be prepared that if you discover a problem you might want to discuss it, and might even decide to pass on the job. If you discover a potential problem regarding the job, such as discovering they have an abusive work culture or they have a culture that wouldn't mesh well with your personality, ask some questions about it to be certain. Don't accept a job you know you can't do, or that will be harmful to you and your psyche. I've seen cases where a person was skilled and could do the job, but there were interpersonal details that couldn't be resolved. That sometimes happens and it is a tragedy, the situations seldom end well.
Be yourself, don't spend energy trying to act a part. This is conversation between (hopefully) future friends. Imagine you are discussing the job with some of your best friends and they're asking about how you do your job, that's all the interviewers are looking for.
Good luck on the interview.
