Instructions
Obtain a 4-star rating for at least four different songs in each of the six different categories. Every time you obtain a 4-star rating for four songs in a given category, this unlocks a challenge.
Beat all of the six challenges in Challenge Mode. Each challenge contains a mix of four different songs. Pay close attention when the game switches to a new song, since you then have to adapt your dance moves to the new beat. Once you have passed all six challenges, the game's final challenge will be available.
Obtain at least a 4-star rating at the end of the final challenge. Contrary to the other challenges, the final one makes you dance to a medley of all the songs in the game. Once you have obtained at least a 4-star rating, a message will pop up on your screen telling you that Dr. Tan's Estate is now unlocked.