The most complicated HUB in SMBX.
I'm making progress on this. 2-6 is done, and 1-1 is well under development. I just realized that, with the shard system, the HUBs are going to be pretty complicated. So complicated I almost had to scrap the idea. You have to play all 15 levels without stopping, but once you get the shard in a area you can play any level in the area without having to do them all. It'll be complicated, but it's happening.