Sky-High Sundae

Sky-High Sundae is a course released as part of Wave 2 in the Booster Course Pass in Mario Kart 8 Deluxe and later as the featured course of the Sundae Tour in Mario Kart Tour. It is the fourth and final course of the Propeller Cup in Mario Kart 8 Deluxe. It is set in a large area (described as a city by its French name) made entirely of ice cream and other candy-related food high in the sky. It is the first course that debuted in Mario Kart 8 Deluxe to later make an appearance in Mario Kart Tour, as well as the first in the series to be announced for two games simultaneously. Despite being the only new course added so far in the Booster Course Pass, it is not the only course to lack a classic course prefix in the pass, as Ninja Hideaway also lacks a prefix.

An image of Sky-High Sundae is in a  for the Booster Course Pass located in the game's files as of version 2.0.0, released four months prior to the course's official announcement. Despite the course releasing earlier in Mario Kart 8 Deluxe, the course icon on the banner, which matches up with the official course icon, points to the course being a new course for Mario Kart Tour instead of a new course for Mario Kart 8 Deluxe. The filename for the course in the internal data for Mario Kart Tour also uses "mob", an indicator used exclusively for mobile courses that were introduced in Mario Kart Tour, such as New York Minute and Merry Mountain. Despite this, the game has been marketed for Mario Kart 8 Deluxe as a new track instead of a returning one.

Course layout
The course takes place entirely in anti-gravity, making it the fourth course to have this trait after Mute City,, and Big Blue. The track starts off in an ice cream parlor that is inside of a giant freezer, after which the racers use Glide Ramps to fly either into or around a giant ice cream cone. Flying into the hole in the cone rewards players with Item Boxes. After that, they land on a chocolate-covered cake with a giant H on it, resembling a helipad. Upon landing, they begin traveling down a light-blue staircase, and at the bottom the path begins curving to the left while proceeding to go up a staircase. At both staircases, there are railings that grant Spin Boosts when driven through. After the upward staircase, the player begins to ascend a slope which splits off into two paths. At the top of those paths, they begin jumping down onto some platforms, which can be landed on both above and below. After the two paths join back together, a path made out of giant ice cream cones circles around an even larger piece of ice cream inside a cup. After turning around, the player jumps between three giant pieces of ice, which lead to a giant ice tray that leads back into the giant freezer where the Finish Line is.

During the race, various advertisements can be seen on giant waffle pieces. At the staircase segment, there are numerous ice cream shops to the right of the path. In the sky, a helicopter modeled after an ice cream cone can be seen, complimenting the helipad cake seen at the beginning.

Mario Kart Tour
Sky-High Sundae appears in Mario Kart Tour, debuting in the Sundae Tour, having been announced one day after its release in Mario Kart 8 Deluxe. The course no longer features anti-gravity, and the Yoshi bartender in the freezer has been replaced by a penguin. The handrails also no longer provide Spin Boosts, though the player can perform tricks by hitting the top of the handrails. Additionally, the rotating Item Boxes on the cake helipad are now completely static. The course is a favorite of Mario (Golf), Mario (Aviator), Rosalina (Chef), White Tanooki Mario, Dr. Bowser, and the Silver and Ice-Cream Mii Racing Suits.

The Sundae Tour also introduces the variants Sky-High Sundae R, Sky-High Sundae T, and Sky-High Sundae R/T. In the second lap of the T variant, the player goes up to the top of the freezer instead of inside it.