Unlockable: 121st Star

There is actually 121 Stars in the game, not 120. To get it, you must first have all 120 Stars. This unlocks Luigi. Beat the entire game with Luigi, defeating Bowser at the end. After this, a new galaxy will be unlocked. Finish this final galaxy to get the 121st Star

Unlockable: Luigi

Here is how to get Luigi. First, get all 120 Stars in the game. Then, return to Rosalina (on the Comet Observatory) and request to fight Bowser one last time. Defeat him and let the credits roll. Thereafter, a message will appear telling you Luigi is a playable character.

Unlockable: Death Count

The Grand Finale Galaxy, which is the secret galaxy that can be unlocked after 120 Stars are gathered with both Mario and Luigi, holds another secret. Once the final Star is acquired with both characters in this galaxy, you will be able to see your death count on your save file. This will allow you to see how many times you died while playing the game with both Mario and Luigi.

Unlockable: Additional Demo Stages

If you are playing a demo version of the game at a kiosk, try holding down the 1 and 2 buttons as you press A and B to start the game. This will unlock additional stages for you to play through.

Hint: Extra Lives

Because you start each game with only four lives (after shutting the game off and turning it back on), you might be in need of some extra lives upon rebooting the game. You can usually get five right off the bat from Toad (he will run around with a letter above his head, symbolizing a letter from either Luigi, or more likely Peach). There are four more strewn around the Observatory that you can acquire, however: * 1.) On the moving green platform below the core. * 2.) Under the stairs leading to the kitchen. * 3.) Right at the top of the observatory. (Once the Red Star is unlocked) * 4.) Underneath the entrance to the gateway to the stars. (Once the Red Star is unlocked) * 5.) Next to the StarShroom (in a crate)