As you collect money from playing minigames, you can use that money to buy decorations for the island and buying new islands. Each decoration are divided on which bar they fill for the island: Food, Fun, and Comfort. Fill all bar for the island, completing the island, and a new minigame will be unlocked.

Minigame	How to unlock
Beach Bash	Complete Waterfall Island.
Parasail	Complete Big Beach Island.
Sandoku	Complete Sunset Lagoon.
Shell Game	Complete Outset Island.
Trijong	Complete Mystic Island.