To unlock Rosalina as a playable character in Super Mario 3D World + Bowser’s Fury, you’ll need to follow a series of steps that revolve around completing the main game and progressing to the Star World. Here’s a detailed breakdown:

Steps to Unlock Rosalina

1. Complete the Main Game:
– You must first finish all levels across Worlds 1 through 6, as well as World Castle and World Bowser.
– The final task is to defeat Bowser in the climactic battle of World Bowser. Upon completing this, you’ll see the credits roll.

2. Return to the Main Map:
– After the credits, you’ll be taken back to the main game map.
– Here, you will notice a new rocket structure that has appeared in World 1. This signifies that you’ve unlocked new areas of the game.

3. Access World Star:
– Head to the newly appeared rocket and enter it to launch yourself to World Star, a new world where additional challenges await.

4. Play Through World Star-1:
– Your first task in World Star is to complete the level titled Rainbow Run. After finishing this level, you will unlock access to the second level in this world.

5. Complete Super Galaxy (World Star-2):
– Proceed to play through the second level, Super Galaxy (World Star-2). Here, you’ll find Rosalina alongside a Luma waiting near the flagpole once you finish the level.

6. Unlock Rosalina:
– Upon completing Super Galaxy, Rosalina will be unlocked as a playable character. You can now select her in any level moving forward. Notably, she has a unique spin attack ability that sets her apart from other characters.

Notes:
– Green Stars Requirement: To access World Star-2 (Super Galaxy), you need to collect approximately 170 Green Stars to unlock the pathways necessary for progression. However, you do not need to gather all Green Stars or stamps within these levels; you simply need to complete the level itself to unlock Rosalina.

With these steps, you can successfully add Rosalina to your roster of playable characters in Super Mario 3D World + Bowser’s Fury, enhancing your gameplay experience with her distinct abilities. Enjoy your adventures in the game!