With the 0.10.1 Creator update, we have introduced a new feature to help users accommodate for the large number of target devices currently on the market - Aspect Ratio Adjustment.

Aspect ratio adjustment determines how your game will look when played on a device that has a different aspect ratio than the game. You have two options which can be selected during the publishing process: overscan and letterbox.

• Overscan - This option will crop the scene in order to retain a full-screen game on various device aspect ratios. This method will prevent Android rejections due to "black bars" on screen.

• Letterbox - This option will maintain the original aspect ratio of the app, but will fill any unused space with the scene's background color. This method is recommended for submissions to Apple.
  Note: The default color is black, but in this example blue was used to emphasize the results.

To fully understand how Overscan and Letterbox works we must look at 3 very important, yet very different aspects of a published project. 

1. Screen size - The size of the screen of the device your project will be on.
2. Display size - This is the resolution of the platform chosen from the drop down in Creator’s home menu. The Display size is unable to be edited. To change the Display size, you would need to select a different platform from the drop down menu.
3. Camera size - This is what you would like people to see on their device when playing your game.

You see that developing a game for the Nook will result in very little cropping when placed on a Kindle or iPhone 5. However, on iPad, your project would have heavy cropping and may be better suited for the letterbox option. If you chose not to letterbox and desired the game to fill the entire screen on the iPad, it would be recommended to make an additional game project built specifically for iPad resolution

Now lets talk about the Camera!

The Camera reflects the part of the scene you would like see on the device. The Display size determines how the contents of the Camera will look when on device. For example, if the Camera is larger than the Display size, the contents of the Camera will be squished into the Display size. If the Camera is smaller than the Display size, the contents of the Camera will be zoomed in or stretched onto the Display size. The Camera works in conjunction with the Display size - the Camera does not know what device the game is running on or the aspect ratio. The Camera only knows what part of the scene you would like displayed on the device and to stay confined within the Display size. For this reason, Camera adjustment is typically done by more advanced users and can lead to problems if not used correctly.

Here is a link to some example templates that demonstrate this new feature - Overscan example template