Does anybody know if there is some kind of ability to make your own world in this game? You know, kind of like if you had a set of preset backdrops to fit different themes, and you could lay out levels anyway you wanted to leading up to a boss level that would mark beating the world. Then world packs could be shared, rated, with the best worlds being put to the top of some top rated list.

I'm guessing that isn't part of the game since I've heard nothing about it, but it would be seriously neat if it was. Imagine a dedicated person basically making a whole Mario game with their own custom levels, organized into worlds.

This is news?

We have had games that offered endless possibilities years way back... Little Big Planet + Minecraft.

Yes for Mario 2D games, now you basically have all previous Mario 2D games in one, and of course endless number of levels.

I added to OP one other example of great level.

Well ofcourse it has endless possibilities. The only limit is your imagination but there's so many other awesome levels there already for those people.

Would be super cool if they had a 3D Mario Maker. But, I'm not sure how it would work...

Yes to all of those, specially the Yoshi demake!

Well, when OP mentioned endless possibilities, I thought you could make more than side scrolling levels.