Gravity Maze, from Thinkfun, is a single-player 3-D puzzle game that requires kids ages 8 and up to use problem-solving skills to solve the challenge. Using the challenge card, the player sets up the board using the 3-D pieces, and then must use the additional add-on pieces specified on the card to get the marble to move from the starting point to the bottom. I always like these types of single-player challenges, and this one was no exception. The plastic pieces are durable and look awesome with their translucent, bright colors, and fit securely into the base. The marble is a smooth metal ball with a good weight, and quickly and satisfyingly drops through the maze. The challenge cards range from beginner level to expert, giving players lots to work with. The beginner level is great for getting the hang of how the game works and how the pieces fit together. The expert level is difficult without being frustrating—it’s fun to finally figure out the puzzle, and the back of each challenge card provides the solution in case players need a hint.