Scrapped Content in Super Mario Star World

Due to SKELUX experiencing several health issues since around the end of 2019, many features of Super Mario: Star World have been scrapped.

Mario's Detour
Mario's Detour was planned to be a second demo for Super Mario: Star World, also being a sequel to Mario's Holiday. SKELUX had already begun development on the game, but scrapped it most likely because it was going to take too much time to develop.

Bowyer's Forest Maze
Bowyer's Forest Maze was planned to be a subarea for Piranha Plant Pond. Possibly, Bowyer, a mini-boss from Super Mario RPG, was actually going to cameo in this subarea, whether it have been as a boss or some other fashion, but was cut, once again, because including him would've taken too much time. However, this is pure speculation.

Arc 2 (Super Mario: Star Road 2)
The second arc of the game, taken from Super Mario: Star Road 2, which SKELUX was developing before planning to incorporate it into Super Mario: Star World, had been announced during Summer 2018, but he had been planning it for more than a year earlier. It is unknown how many courses there would've been in the second arc.

The second arc's final boss, SKELUX's avatar, a Chomp, was planned to be quite literally the largest boss ever in any Mario game, also having the ability to teleport. It might've been the threat that was hinted at in Mario's Holiday, as one of the Signposts of Future Predictions read the following: "A new threat....The entire world, could it be in danger?". The second arc would've had two endings instead of one. Neither of them would've been good, but, rather, one would've been bad and the other would've been sad, but less bad.

The following three side courses from Super Mario: Star Road 2 might've been planned to be included in the second arc: There was another course included in this batch, Breezy Boardwalk. However, it seems to have been repurposed as the location of the Yellow !-Switch included in the first arc.
 * Cloudtop Citadel
 * Sound Step Seas
 * Autumn Airway

Course 16: Switch-Step City
Switch-Step City was going to be the 16th main course with a city theme. Since he already finished the course model, SKELUX stated that he might add this course as it was previously envisioned in an update, or strip it down with simpler missions. This course was hinted at in Mario's Holiday, as one of the Signposts of Future Predicitons read the following: "A 16th stage....A large new world will be visited?"

Course 17
Course 17 was planned to be a creepy, haunted main course, though it is unknown whether or not it was going to be similar to Gloomy Garden. SKELUX confirmed that this course has no chance of making it into the game.

Yoshi
There were going to be modified rideable Yoshis in the game, which would've replaced his playable role. Different colors of Yoshi were planned to be in the game and would've been found in colored eggs. Their locations, however, remain unknown. Each colored Yoshi would've had a unique ability, similar to those from Super Mario World.

Costumes
Costumes for Mario to change into were going to be present in the game, as one of the Signposts of Future Predictions from Mario's Holiday read the following: "Costumes....Mario learns some fashion sense!" However, it is unknown if Costumes could've been found and/or purchased through means other than the Shop. SKELUX did, at one point, tease that Costumes could've had special abilities. For example, he was talking about possibly allowing the Cheep Cheep Mask to give the player a fish-eye lens to play the game with.



The Shop
There was going to be a shop where players could exchange their Coins and Lives for Items and Costumes. The Shop would've been located inside of the ?-Block in the new hub world area, but it is unknown what NPC would've been managing the Shop or what Items and/or Costumes would've been for sale.

Minigames
SKELUX stated that he was planning on adding 10 new and modified unlockable minigames playable through arcade machines. These would've had themes based on the courses that they are unlocked in, such as the Chucking Competition from Chuckya Harbor.