The main difficulty is combining two colour bombs. However, the board is very restricted at the start, so it's very hard to create colour bombs on the first time.
The player has to do all of the orders in just 30 moves, considering that combining two colour bombs can cost most of moves provided, activating other special candies may not enough moves.
Mystery candies are isolated from the main board and covered with marmalade. So, the player has to use special candies to reveal them. Even if they are revealed, they aren't always coming out good outcomes.
The orders are worth 17,000 points. Hence, an additional 13,000 points is required to earn one star.