YMMV / Nimbus

• That One Boss: There's only one boss and he's pretty difficult.
• That One Level: This could be said about many of the levels (especially on Hard Mode), given the nature of the game, but special mention goes to some of the bonus levels, most notably Scrapyard 4-3, which has a difficulty rating of 12 stars (only one level in the game has the previously thought to be maximum difficulty of ten stars and it, too, is a bonus stage). The creators stated that these levels were too poor to make it into the game, so at least they're acknowledging their difficulty.
• That One Sidequest: Collecting coins makes certain stages much harder than what they'd normally be due to some of the requirements in order to get them. Collecting them unlocks new ships and trails.