Molly played a simplified version of the primary song "I pray in Faith". I gave the kids the challenge this summer to each pick a Hymn to learn to play. The older three had actual hymns from the hymnbook but I let Molly do a simplified song.
Ian also played the theme to one of his favorite computer games, Kerbal Space Program. He went and found the piece online and printed it out himself and asked the piano teacher to help him learn it.
BTW, this is a great app. We are addicted to it at our house. It is nice because a game goes pretty quickly. If we have a five to 10 min wait we can get a game in, no problem.