The main mode in Super Mario Run is called World Tour. The free version features 3 levels from World 1 and a 20 second trial of the castle level from within the same world.
The good news is that paying $15 unlocks all 6 worlds and 24 levels including 7 castles. Whilst that seems like not many, it’s important to remember that there’s three sets of five coins to collect in each world that are incredibly hard to get and there’s also Toad Rally which allows you speed run against other people on the internet in order to gain Toads.
It’s also important to remember that there’s currently six characters who all control quite differently. For instance, Toad is a lot quicker than Mario and Luigi can float for longer. This in itself makes World Tour replayable.
The levels are:
World 1-1: Up and Over
World 1-2: Wall-Kicking It Underground
World 1-3: Paratroopas in Mushroom Valley
World 1-4 Bowser’s Castle Hangout
World 2-1: Ghost Door Deception
World 2-2: Sky-High Lifts and Leaps
World 2-3: Treasure-Hoarding Swoops
World 2-4 Airship Cannons.. Fire!
World 3-1: Big Spiny Blitz
World 3-2 Bullet Bill Barrage
World 3-3: Shell Me The Way
World 3-4: Fire Bar Castle! Youch!
World 4-1 : Cutting-Edge Spire
World 4-2: Slope To Sucess
World 4-3: Danger High and Low
World 4-4: Firing The Airship’s Burners
World 5-1: Lakitu’s Revenge
World 5-2: Pokey Vaulting
World 5-3: Boohind Lock and Key
World 5-4: Rings of Fire!
World 6-1: Land of Spikes
World 6-2: Switch Ghost House
World 6-3: Throwing It All Overboard
World 6-4: Bowser’s Bob-ombing Run