Just sandboxy

引用自 Pouf：

They are the easiest, and you have a lot of rails. What's the point? Is there some secret unlocking if you manage to clear them with a certain number of rails, or something like this?

The "#" world is just a post-game section where you can play around with the mechanics; there are no secrets hidden here :)

Yep, I also thought there's some kind of crazy mechanic going on. Like if I have 75 rails to solve all the levels in # section. Or number of available rails depend on how much bonus levels you solved. But nope, nothing like this.

It's still the only thing I don't like in this great game.
Having it as a 'world', so that I feel obliged to play it in order to properly finish the game, feels bad to me. I don't really enjoy sandboxes in any game I own.
Yes, I finished the original # world, but solving the levels just felt like cheating and therefore unsatisfying to me, as you don't need to use some of the already given track pieces and mechanics at all.
I hope it was changed to not be obligatory in order to unlock the hidden level.