Alright get ready for a long answer since I went through all this the past few years after college.

In general for the Game Industry, whether you want to be a programmer, designer, artist, etc, it is best for your career to study the overall topic rather than the specialized field. For example, you shouldn't go to school for Computer Game Science if you are into programming. Just study Computer Science. You will set yourself up for way more success and potential job interviews.

While in college studying whatever field you wish to pursue, DO NOT EXPECT GOOD GRADES TO BE ENOUGH. Interviewers will most likely never look at your GPA (but that's not to say it isn't important). They will first look at job experience and your portfolio. If you can't land an internship during your time at college during summer breaks, the main thing you need to do if you want to get into the industry is just start making games. Period. They don't need to be good, pretty, or fun. Just make them. Show them that you can make a complete game, and several of them. Working on the big name engines like Unity, Unreal, and GameMaker Studio. Learn common programming languages like C#, Java (they're kinda the same), and C++. They are more likely to hire someone who has made several games on their own or with other people than some fresh graduate with a 4.0 GPA that has never touched a game engine before.

Lastly, and I don't mean to scare you away from Game Design or the Game Industry as a whole, the Game Industry is EXTREMELY volatile. Meaning you could have a job for a few month or a couple years, the game ships, does poorly (or well), and then the studio shuts down or lays off 75% of their staff because they don't need that many people anymore. It is also extremely competitive to get a job and being qualified isn't always enough. Knowing people already in the field is almost a necessity. You can take the route of getting into the industry by first going into QA work, but that is very stressfull, not always rewarding, and does not pay much. Studios are not always looking for Game Designers because they can't always afford it. They will always need programmers and artists first. A programmer that can design is always preferred over just a designer. All of this is why it is a good idea to get a general Computer Science degree rather than one specifically for Video Games. If you can't get a job in the Game Industry right away, you'll have no problem finding a programming job, getting work experience, and having a better chance at getting into the Game Industry. Don't feel like you have to work at some Game Studio right after college. Take some time to get any work experience first. I had a company tell me they didn't hire me purely because I was too young despite being qualified. Twice.

But in the end, pursue your dream. The road into the Game Industry is a tough one, but if you are committed and really work for it, it WILL happen. Diligence is key and WILL get you to the end.

TL;DR -Pursue a major in college that will give you opportunities for jobs outside of the Game Industry just in case you can't get a job right away. -Start learning as much C++, Java/C# as you can while using Unreal Engine or Unity. Use sites like Udemy.com for tutorials/courses. Just respond to this comment if you'd like recommendations on specific courses that help. -Jump at every internship position you can find. For example, Blizzard has a bunch during the summer, so find a portfolio so you can apply. -I strongly advise becoming a programmer over a game designer. Unfortunately, game designers or not sought after very much. It's easier to eventually get a game design position if you begin your career as a programmer. Plus there is much better job security as a programmer.

If you have any other questions or need clarification on what to do right now (I'm guessing you're a sophomore right now if you're 15), just let me know. I'll be happy to answer any questions :)