I recommend majoring in CS/CSE/EECE. You need to know CS 111 material for low-level programming and the vector/matrix material from Math 33A is everywhere in the engine. Higher-level stuff, like marketing, design and scripting don't require a specific major; most of the game programmers I worked with got their B.S. in Computer Science but the designers and scripters came in with North Campus degrees and/or worked their way up from QA. Helping to sell the product is a tougher one; I don't know what the qualifications for game marketing are.