I think the best part is watching your creation grow through the interactions and events of a roleplay.
Something along those lines happened in the last Pathfinder campagne I played with my friends:
The gods were actively playing around in the world and causing suffering and destruction, but in recent years (1k years or so) they slowly lessened their grip on the world. Insert our group which fights to eliminate the influence of the gods on this world. One PC hated the gods and evil stuff. You could say he was a righteous guy, that wanted freedom for everyone and to protect the mortals from the gods. (shortened a long character to the outlines)
My character was a human and later transformed into an immortal and she was sealed the last 1k years. She once created an empire which was spared from the whims of the gods. To ensure that she would always be there to protect her people, she searched for a the secret to immortality. An evil god tricked her into sacrificing a let's just say large number of infants to gain immortality and protect her people from the chaotic world. Note here nations and continents were destroyed and created on a daily base in the setting, her empire was one of the very few exceptions which came from her personal power. Should she die millions upon millions of her people would die. So she did it and was later in an uprising sealed.
Back to the current time, the other PC got the information that my character sacrificed 100k infants. The whole thing was explained as it was a moral dilemma: Kill 100k or sentence millions upon millions upon millions to death? She choose the 'lesser' sacrifice which resulted in the destruction of her empire. All in all her decission ended in the same ending, except that she is still alive.
How would a righeous guy react to that? (The face of the player was simply the best, since he didn't want to metagame and had no idea of the background

) Is it still evil if it is done to ensure the safety and prosperity of the majority? What is good? What is evil? Those were the question that the character needed to think about. I can't really wait for the next sessions
To return to the topic: The growth of the creation, be it universe, nation or single character. That is the best.