Before reading any further you have to watch Ed's vid to understand the rest of the tutorial, I am not going to repeat his great lecture here again...
For this tutorial I'm using a Window Size of 360x640 (9:16 Aspect Ratio), the Layout Size is 480 x 640 (3:4 Aspect Ratio) and the (Ed's) Safe Zone is 360 x 640 (9:16 Aspect Ratio again) at positon 240, 320 (centered).
Note: The 9:16 is the smallest Aspect Ratio and the 3:4 is the biggest. If all action takes place in Ed's Safe Zone and you cover the rest of the layout with some filling your game will be displayed almost similar on all mobile devices...
Note: You can use any sizes for your game as long as they are in the right Aspect Ratio.
One more important issue, at the start of every layout start the code with:
This will center your game.
If you did everything right the yellow Safe Zone is centered on every device, showing a little bit more on the screens with a wider Aspect Ratio.
Ed's Safe Zone should be deleted or set to invisible before publishing...
At page 3 of this tutorial are some links to Slappy Feet. I hope this little contribution will be clear, if you have any questions drop a PM or send an e-mail to Franco Palmieri at info@fronne.nl and I will answer for sure...
Time for some screenies, I will show all layouts of Slappy Feet (my first game):