There are 3 different types of modes on the opening screen.
This is where the story develops.
This is a new challenge. Players get at least 1 badge after clearing a stage.
You will need to finish Campaign to unlock Expert. Expect to literally be defeated a multiple amount of times As Expert mode is quite literally for "Elite players", Hence it being superbly difficult compared to Hard mode, and incredibly hard for new comers especially.
Plays the first cutscene again.