"think of your game" or "think about your game"?

"Think of your game" has two meanings. It can either meam "Imagine what your game might be like" (which is what your developers did before they started writing it) or "Think about the result of your actions on the game" which is something someone might say to a professional footballer who was drinking and clubbing too much and damaging his performance.

Of your two options "Think about your game" is the better one but better still would be "Just think about your game" because that says that the customer can, as you say, think only about the game and about playing it. They don't have to concern themselves with hardware compatibility, the installation process, installing upgrades or any of the other ancillary stuff.