I was thinking about the brother/sister concept and was reminded of the nursery rhyme Jack and Jill. I then looked it up on Wikipediea. Here is the link: Jack and Jill I'm thinking that many parents know of this rhyme and tell it to their kids, so maybe if they see the video game with a short description of the story, they might buy it for them. If the game does not have too much violence and focuses on puzzle solving, we might be able to pitch the game as semi educational: the kids will get to know the story, and remember the moral while also learning how to problem solve. If we are okay with this idea, maybe the kids names can be Jack and Jill. Nowhere in the nursery rhyme does it mention a father, however, there is a mother. As suggested in one version of the rhyme, the mother punishes Jill for causing the disaster(Jacks fall). Here's a quick story, Jack and Jill go up the hill to fill a pail of water from the villages only well. They fight over it causing the water to spill and Jacks crown falling in the well. The water can be symbolic of life and the crown of power. After losing both the water and crown, the village is in trouble. Now both Jack and Jill must enter the dried up well to retrieve both. The well however is dry, so the two must work together, going into the depths of the world beneath the well to find the water and crown they so desparately need to survive. I could continue, but this post is becoming lengthy and I thought maybe others would like to fill in the blanks...