After 8 years of being in the game I have finally added Frosty Plains and Fright Zone as their own leaderboards. Unlike the main story, there will not be individual chapter categories for either side story, since they are each only 2 chapters long and all of their levels are shorter than typical story levels. Additionally, the levels from each campaign have been added to the pool of individual levels, excluding Fright Zone's battle stages as they do not have an in-game timer (though I am open to including them if there is enough demand).

The Frosty Plains category requires you to play through all 6 levels of its campaign, starting at Frosty Plains 1-1 and continuing along the main path until Frosty Plains 2-3. As with the main story, the time star is not required for 100%. On versions 1.0.9 through 1.2.5 Frosty Plains was a normal mode campaign, so that has a separate leaderboard, but the default is hard mode.

The Fright Zone category requires you to play through all 6 levels of its campaign, including the two battle stages, starting at Fright Zone 1-1 and continuing along the main path until Fright Zone 2-2. The time star is again not required for 100%, however you must obtain 3 stars on both of the battle stages (ie a score of 55000 on B1 and 60000 on B2).

As Fright Zone is the first campaign to require battle stages, here are the (load removed) timing rules for arenas: time starts upon releasing the go button on the vortex shop to enter the arena, and ends either on the first repeated frame right before the arena complete message displays or if there is no repetition then on the frame that the arena complete message first displays. To get the total load removed time for a level with multiple arenas, do this process for each arena and add up the time. (This doesn't matter for any level on the leaderboards, but all time spent watching a cutscene in the arena or watching an ad in the arena, which is possible in special event levels, is removed from the load removed time.)

Happy running everyone!