Hey op, this really depends on what you want to do specifically. Since you said game developer I'll assume you mean the technical side of things.
Assuming you want to go indie or small team or have input in what the game is:
Know what makes a game fun.
Be able to critique your own ideas.
Be prepared to change, pivot, adapt or start over.
Know who you're targeting and (assuming you want to make money) have a plan or flow as to how this game will make you money.
Have some understanding of psychology.
Have some understanding of marketing.
Good communication.
Assuming you want to go big leagues in an established company:
Not much especially that I can think of. Have culture to fit the company, be hungry, driven, be able to take criticism but also defend your ideas, excellent communication.
Common to both:
Obviously the technical ability - be that in the specific technologies the company or you want use or competency in something similar that you can adapt learning anew from.
Portfolio of bangin past work.
Enthusiasm, passion etc.
Contacts and network of relevant people to what you want to do.
Roadmap to getting there:
1. Tertiary degree or study are useful but not completely necessary. For sure they will help keep you focussed on learning skills you'll need but you may find that you can do that with free resources on your own. They are also great at opening you up to internships, networking opportunities, events, jobs etc. But by joining communities and keeping an eye out for things around the place you can do this on your own too.
2. Build things. Have a portfolio of work to show. It shows that you are competent to at least that degree and have enough drive to actually make something. If you don't want to do your own thing then contribute to open source or community projects.
3. Know people. Again, super useful for breaking into a job or opportunity. It will be hard otherwise but if you're a beast then you'll make it.
Edit: Re uni/college degree - think really hard about what you actually want to do. If you're going to be doing mostly technical things but in regards to games then it might be better to do a cs/tech/programming focused degree with game flavours as minors or added in your own time externally.
If you want to do "game design" (good luck) then a games/interactive entertainment degree is probably what you're after.
Animation and more creative side? Do an animation/creative industries degree. It's not hard, just make sure you give it thought.
Last edited by Solax; Mar 21, 2016 at 12:58 PM.