1. Start by downloading the Fill In 3D game from the App Store or Google Play.
2. Once the game is installed, open it Up and you will be presented with a 3D grid of Squares.
3. The objective of the game is to fill in as many of the Squares as possible with the same color.
4. You can do this by tapPing and dragging on the Squares to fill them in. You can also Rotate the grid to get a better view of the Squares.
5. As you fill in the Squares, you will be presented with new challenges such as trying to fill in a certain number of Squares in a certain amount of time or trying to fill in a certain pattern.
6. Keep playing until you clear all the challenges and fill in all the Squares.