You need to put forth an incredible amount of work into your portfolio, as well as your understanding of programming overall. Having recently been accepted to graduate school for programming, i can guarantee you will see results directly proportional to the effort you put in. A portfolio looks good, but you need a substantial understanding of the language you are working with, as well as programming concepts as a whole. Often times interviews are done (even if just over the phone), and you may be required to explain exactly how and why you made the choices you did in your work, without the time to sit there and think it over.
Don't want to scare you off, just ensuring you understand the degree of commitment it takes to enter the world of game programming. Playing games might be fun and easy, but making them is not for the faint of heart