These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Super Mario 63
Awesome Music: Any of the remixes that were put into the game, and Galaxy's Floater Land Theme.
Game Breaker: Unfortunately for the designer, there is obviously no way to ensure an entirely linear way of game progression, since certain areas can actually be accessed prior to their storyline appearance.