Graphics are bitmap files, in 32 bit format. Transparency effects are achieved by using the color with RGB values R=255, G=178, B=178.
Objects may be any size, and may even have different sizes between frames.
Tiles may be any size, but the height must have exactly half the size as the width. Corners are recommened to be cut off using transparency to create a diamond since the game will join the diamond shaped tiles together to create the isometric view. If you don't lopp the corners off, the game won't care, but will draw the corners in. This may be used to your advantage however to create maps without the jagged edges...