I've recently published a small iOS game, Flipz (https://itunes.apple.com/us/app/flipz/id775988938?mt=8).
Now, I've gotten some feedback that I really need to add background music. Unfortunately, I don't have any experience composing/creating music and my guess is that this is nothing you can learn in a weekend. And I can't pay someone to create music for me...
So, puzzle game developers out there. Is background music really something you have to do? Does it actually add to the fun?