LogFAQs > #945471718

StealThisSheen posted...

You have to beat whatever the highest level you have unlocked is to unlock the next. So, for example, if you have 2-1, and you beat it, you'll unlock 2-2, so now you can select 2-2 and hopefully beat it to get 2-3 and so on.

Small correction: You need to have beaten EVERY level prior to the level you want to unlock. I beat 3-1 on my own to unlock 3-2, and then I had 3-3 unlocked because I beat it on someone else's pick, but even after beating 3-3 again on my pick, I didn't unlock 3-4 until I beat 3-2.