If children play tag, do they take it seriously? No, and yes.
No, because it is a game. And they don't even need to be aware of that, nor do they need to understand the concept of differentiating between games and the real thing. What is it then that makes them play? What distinguishes playing from being seriously?
This is not a question that I have an answer to already, but I really enjoy thinking about it. I probably will write more about this in the future. Until then, I'd like to recommend American Beauty. It is a movie about being alive and having nothing to lose. And I guess the latter is essential to playing.
And yes, because they are involved. They devote their entire self to the moment and don't hold off. They honestly try their best. Still they play. Isn't that amazing?