Useful tool for designing levels with tiles
Gamesalad currently does not provide a snap to grid feature when working on your scene, which can make it kind of a hassle to place tiles in the exact place you want it, and a lot of actors acting as tiles can slow down your game due to the large amount of actors being processed in the scene, I know of a very useful tool called Tiled that allows you to use tilesets and place each individual pieces onto a space, you can also save it as a PNG file, so you can drag it into your scene and add some actors on the tiles to add a collision box. I hope this helped!