I'm working on a small-ish 2d fixed shoot 'em up for iPhone.
I have a master Game object that stores lives, score, current level, etc...
The game will have some other persistent attributes like Music and Sound mute state, difficulty level (easy, medium, hard).
Should I put those attributes in the Game class or should they be on their own?
What's the rule of thumb to decide how to partition attributes among classes?