Sarasaland Adventure v4.0 (SMBX) - Slipslide Skytower (6-2; both exits)
Info: https://rpgmaker.net/games/4216/
Now this level is interesting. You're basically navigating a floating tower in which, strangely, you must DESCEND while sliding in a few of the sections, while needing to ASCEND other sections by manipulating switchblocks and such. It's pretty crazy. This level isn't really that difficult, but you need to make sure that when you start sliding that you DON'T move Mario in any way, otherwise you're sure to pay for your mistake by dying. This is also a level where you can earn many 1-ups, due to how the enemies are positioned on most of the sliding sections. You also end the level (and earn the last flower, too) while in mid-slide, which is really spiffy. This is one of my favorite levels. The stars, nor the secret exit aren't really too difficult to find, either. Pretty cool & fun level overall.