I have had trouble finding any information about what sort of questions could be asked

Really? You must not have tried very hard. Just Google "interview questions" - you WILL be asked many of the same questions non-game applicants get asked. The interviewers want to find out if you're going to fit in with their people, so a lot of the questions are people-oriented. The interviewers want to find out if you're qualified for the job, so they'll also ask you how you would handle job-specific problems.

Because it's a game job, you will also be asked "what's your favorite game" and "why's that your favorite?"

Because it's a programming job, they'll also test you on your programming. Many other people have asked (here on this very forum) what kind of questions they'll be asked, so you should look through other threads here on this forum. And I'm sure others will come along and write more here as well.

BUT - not only will you have to answer questions, you ALSO have to actually ASK some questions. You have to ask good questions. Don't ask "how many vacation days do I get" or "are vacation days accruable" or "what's the sick days policy." Ask intelligent questions about the company, past projects, the project you'll be working on (realizing that they cannot tell you specifics unless you signed an NDA already), who you'll be working with... So you have to do heavy research on the company. Go way beyond their website and what Google turns up on the company name.

I don't know if you can expect to find unity-specific examples of interview questions anywhere. In general, the team will probably put you through a few design or thought exercises, have a technical discussion with you, and probably have you do some whiteboard coding or code critiquing. Advice for all of this, as per general, is relatively well known -- listen, repeat, clarify before attacking a solution, think out loud, and do not hesitate to change directions on your solution if it seems you've got stuck -- I've failed one interview by looking for a log-N solution that I was sure existed (and it did) but was more complex than I imagined, and because of complexity was actually no faster than the linear solution that was obvious. If you think you need to backtrack, its actually an excellent time to bounce ideas off your interviewer -- "I went this way because X, but now I see Y. That makes X hard, but maybe Z is a better solution. What do you think?" They're not going to give you the solution, or probably even tell you whether they'd choose X or Z, but they will almost certainly help you puzzle things out some more, and its not the kind of thing they'll dock you for if you are going about it intelligently. They aren't looking for people who know the solution to every problem cold, they're looking for people who can find solutions to problems they maybe haven't seen before.

Practice questions -- even or perhaps especially the non-technical ones. The goal isn't to come up with a script, but ask yourself the questions and write down the answers. The goal is to simply bring relevant information from your experiences to the top of your mind. You don't want to wake up the next morning regretting that, under pressure, you failed to recall that really great story you have about solving a similar problem.

And as per usual, I will recommend you to buy and read "Programming Interviews Exposed" -- its in its second edition last I looked, and the best $30 a programmer can spend. It covers everything from resume tips, to typical soft and hard questions, to thought exercises, to how to dress, to how to negotiate a salary. Buy it now.

As someone who recently went through an interview at a game company that uses C# and Unity3D I can share some of the questions I got. I didn't really prepare for anything, as I didn't really figured it would be a technical interview (it was the first interview I got and it was a mix of some regular questions and technical), but all went well.

I got asked some general programming questions like what inheritance is, what polymorphism is, what are interfaces and stuff like that. I also indicated I was specialized in graphics programming, so I got a few specific questions about that as well (why would I use a quaternion, how do normalmaps work, why are they in tangent space and why)

Also on some other topics because I stated I had experience in that area (multi threading).

In the end just be honest if you don't know the answer to a question, but obviously there are some things you simply need to know to keep up (where that bar sits is up to them of course)

Anyway, good luck! :)