The barrier will be expanded by progressing through the advancements. You can always look at the advancements by pressing the shortcut key (depending on your controls) or by pressing Esc -> Advancements.

The purple advancements are the key advancements, all of which have to be completed to progress and expand the barrier. Each of the first 3 stages has its own advancement tree with some of them being purple, these are the ones you should focus on. To be able to access the End you will have to visit every island and complete all the advancements though, even the white ones.

Thank you! The challenges are all implemented in the advancements, which represent the overall progression of the player. Most of the og challenges are worked into the respective categories (Craft 10 fences for example would be in the Crafting category here)

Thank you for your feedback! The goal of this map was to implement the latest features while keeping up the old Skyblock's flair in any of the islands. That's why we deliberately refrained from pasting structures into the world, like DrTrog did in his map. It actually has been our motivation to create this map in the first place because noone else seemed to have done it before and the one by DrTrog was, in our view, too much of a difference to the original Skyblock. But as for all, tastes differ, and so they do here.

Thanks for your compliment, we are sure DrTrog worked out an astonishing map nonetheless, although we did not play it yet. The download and view numbers surely prove his effort :)