The movement of the balls within the game area is controlled by gravity, which can be adjusted to "up" or "down" by tapping on the screen, and white lines, which act as surfaces that the balls bounce off. On most levels there are lines already in place, but you can also add your own by drawing on the screen.
However, the length of line that you can draw is limited, with the available amount varying between levels. This means it's not always possible to draw a direct line, for the ball to run down, from the starting point to the finishing portal. Instead it is necessary to strategically place lines, so that, in combination with gravity changes, the ball bounces and moves in the desired direction.
Gravity changes are a very important part of the game and it is important to get their timing right, especially on the later levels. They can be used to move the ball from one end of the playing area to another, to change the arc of ball travel, and (in a series of quick changes) move around obstacles.
Gravity Pro has 60 levels. In the early levels you may need only draw a single line and make a single gravity adjustment, but later levels require the drawing of multiple lines and several gravity changes. Additional game play elements are also introduced, such as red lines, which must be avoided at all costs.
Gravity Pro is a worthy addition to any Windows Phone device and is a great indie game, but will especially appeal to those who like puzzle games that require a little brain power to complete. Highly recommended.
Marketplace description:
Draw lines and control gravity, so that the ball ( or balls) hit the target. Gravity Pro is an challenging physics-based puzzle game which consists of 60 levels.
Gravity Pro can be downloaded from the Windows Phone Marketplace for free.