Planet of grass and ice.
This world is made to feel good in it, like when you cross a beautiful grassland with moutains in the horizon. The concept is that the kid would have to find pieces for ships (with color marking.)
Auroras are showned in the poles and the dark side, making this beautiful and enjoyable for kids even in the darkness. also, it makes it less scary to be in the dark, even though a light blue hue will light up the dark side.
Mountains and great ark of rocks are the major land marks, plus a big snowman.