But if you’re an expert puzzler, you might be looking for something a little more challenging. Each of the golden regions represents a “Challenge” that’s ready to play. “Challenges” are ultra difficult puzzles that have multiple game modes. e.g. Blitz mode and Blind mode together. As you progress through the game you’ll unlock new golden regions and face new challenges. The idea is to keep collecting golden regions and fill up all the maps.
Here's a video to explain it further.