As the initial concept for Racciman's world, was that it would be run by a family of gods who were still children, and were making it as a 'Practice World'. This led to the notion that it would be flat.
Gravity on a flat world would, under physics as we know them, behave quite oddly. I didn't want that. I wanted a world that would appear on the surface to be a 'normal' world, but that every so often you would run into some aspect where the gods had goofed. So I declared by authorial fiat that the gravity had been magically 'fixed' by the gods on ONE side of the world, the other side of the world has insufficient gravity to maintain a breathable atmosphere, and is uninhabitable. The gods also magically provided a small sun and a moon and put them in orbit around the planet. The sun and the moon actually share an orbit, and are exactly opposite each other at all times. This means that the moon never gets any sunlight and thus remains dark. Oops!
To create 'normal' seasons the gods set the world to swaying back and forth like a teeter-totter. If you look at the world from above, so that it appears perfectly round, the pivot point goes across horizontally. This imaginary line also marks the sun/moon orbit path. During the year or 'cycle' the top part of the world swings up and the bottom swings down, moving the top closer to the sun's daily path across the sky and the bottom further. This creates summer in the north and winter in the south. Then the world swings back the other way, and you get summer in the south and winter in the north, just like you would on an ordinary round planet.
Obviously such a world would be lacking the normal compliment of solar system, and star systems and so forth, so the gods set it floating about within an ordinary galaxy in the hopes that the night sky wouldn't get too boring, and actually the night sky tends to get quite bright, if somewhat unpredictable. There is no following a conveniently placed north star on *this* world, as the stars that come within view tend to migrate about the sky in an apparently aimless manner. Belatedly realizing that this would make extensive calendaring difficult, the gods provided a century tree in the middle of the world, that blooms every hundred years, and the phoenix who rests in its branches, and flies around the world in a day every thousand years. Just so that there would be some sort of marker longer than a year to help the inhabitants keep track of the passing of time.
And finally, in a burst of caution, the gods decided that it would be best not to let the inhabitants of this peculiar little place mix freely with the rest of the universe, and they placed a barrier around the inhabited half of the world, that prevents the passage of matter, magic or souls without the assistance of a god or immortal, but allows light to pass freely.