To unlock the Secret Worlds in Super Mario 3D World, players need to accomplish specific tasks after completing the main game. Here’s a detailed breakdown of the requirements and the subsequent unlocks:

Requirements to Unlock Secret Worlds

1. Complete Main Game: You must defeat the final level, which is located in World Bowser. This is essential for progressing to the new content.

2. Collectibles: Gather all available Green Stars, stamps, and reach gold flags in every level prior to the final World Bowser stage. Achieving these completions is critical, as they are necessary to unlock the portals to the secret worlds.

Unlockable Secret Worlds

Once the above criteria are met, players can unlock and access three additional worlds:

1. World Star
– Unlock Condition: Complete the final level of the main game (World Bowser).
– Description: This world consists of nine new courses. The difficulty level is moderate, offering players a blend of new threats and challenges. Access to World Star is through a rocket located in World 1 and only requires the minimum number of Green Stars necessary to progress to the final Bowser level.

2. World Mushroom
– Unlock Condition: Complete the final level of World Star, known as Cosmic Cannon Cluster.
– Description: This world features remixed versions of previous courses, testing players’ skills with heightened difficulty. Expect familiar stages with new twists and increased challenges, which will push players to adapt their strategies.

3. World Flower
– Unlock Condition: Complete the final level of World Mushroom, titled Broken Blue Bully Belt.
– Description: This is considered the ultimate challenge, containing the hardest remixed courses from the game. Players looking for a test of their platforming prowess will find World Flower to be a formidable challenge.

Summary of Secret Worlds Unlock Conditions

| Secret World | Unlock Condition | Description |
|—————|—————————————————|———————————|
| World Star | Beat the final level of the main game (World Bowser) | 9 new courses; moderate difficulty |
| World Mushroom| Beat World Star’s final level (Cosmic Cannon Cluster) | Course remixes; increased difficulty |
| World Flower | Beat World Mushroom’s final level (Broken Blue Bully Belt) | The hardest remixed courses |

To fully engage with and unlock all secret worlds, players must explore thoroughly and demonstrate skill across all previously available levels. Collecting all Green Stars, stamps, and gold flags is not just recommended but essential for progressing to the final levels and unlocking these challenging worlds.

Important Note
No additional paid content or downloadable content (DLC) is required to access the Secret Worlds. All content must be unlocked through gameplay and completion of the challenges presented throughout Super Mario 3D World.