As children grow older these questions change too, and maybe more concrete. Why can I not receive communion when I am in mortal sin? What is mortal sin anyway? What does the Church teach about capital punishment or self defense? How can God's love and justice be reconciled? Why does he condemn certain people to hell if he is a loving God? And the questions go on and on.
But how can I answer these questions? They usually come in unexpected moments without time to prepare to give the perfect answer. Even if I do know the answer I might ask myself several other questions related to the matter while I am giving the explanation, and I hope that my audience will not put them to me. One answer usually opens up a whole new world of questions. Peter warns: "Always be ready to give an explanation to anyone who asks you for a reason for your hope" (1Pt 3:15)
Unless I have the courage to inform myself about these matters I will be caught off guard. It takes courage, and yes, often humility to recognize my ignorance. Sometimes the answer is simple to find, while other times it may not be found summarized in a few sentences in a book, but need to be meditated upon.
There are some great resources that one can use to know how to respond to these 'big questions'. For any Catholic the Bible and the Catechism of the Catholic Church (or the Youcat, which is an easy-to-digest way of reading the Catechism, especially aimed to young people) are a must. While they are both available online (I have not found the Youcat online yet), you really need a printed copy or at least one on your iPad. It is also important to have some book of apologetics. I have found Apologetics and Catholic Doctrine by Archbishop Michael Sheehan very useful, but there are other good ones available.
With a good, albeit small core 'library' I can start to answer my children's questions, and be their hero not only in games, but also of faith.