In 2D Mode, the blocks are arranged on a single flat surface. In 3D Mode, the blocks are arranged in a cylinder, as if they were attached to the outside of a can. In 2D Mode, the cursor will stop when it reaches the edge of the screen, but in 3D Mode, the cursor will wrap around, allowing you to move left or right as much as you want. Make sure you watch the blocks at the back. If they stack up and reach the ceiling, you're history!

It may take a bit of practice to get the hang of 3D Mode, but it provides a new, fun way to play!