Like the post said, it's all about getting through the interview and most of the time the interview isn't about how good of a programmer you are.
Yeah, the interviews and tests they do normally don't have anything to do with the programming prowess, but rather your ability to understand the problem and problem solving abilities.
Though, also, you don't have to work for a company to have a job as a game programmer. You could just look into indie teams and start programming for them or start your own game and program it. With things like kickstarter and the other crowdfunding sites, you can always try to get backed. If you are younger than 18, then just be patient, you have plenty of time to hone your skills and land your dream job.