video games are 100% computer code. visit a computer programminginstructor and tell him what you want to do; see if hisclasses will give you the skills/knowledge you seek.
Look on the box of your favorite game and find out what program it is written in. Go buy the manual from Amazon or some other bookstore. Read the Book. If you still love it after you have read the whole book (without skipping the boring parts), then the next step will be getting a certification in that programming language.