What about something like "in_order_traversal", which is an algorithm and you need to keep track of the traversed stack. You could either write it with functions in which case you would need to pass the stack as a parameter and have a constructor/initial state version of the function that passes the stack to the main function, or have a functor/function class that keeps the stack internally.

So there are 3 hard problems in programming.

1. Naming things, and .. I forget what the other one is.

likely "game" would be something that would be about the whole game, including graphics, sounds, etc.