Here's my advice to some of the successful App makers of Angry Birds, Cut The Rope, et cetera: Make a version for kids (of different ages) and call it Angry Birds Junior or something. Children loves to play to games their parents play, my son of five plays Angry Birds and Cut The Rope, but some of the puzzles are just too hard.
The good thing here (and that's the business case) is that the investment is minimal. It's only level design, all other things can stay the same. Another good thing is that there's already a lot of people playing these games, so it's easy to promote it.
This is almost a no-brainer, but I am still waiting…
Thank me later :-)