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: ROSE Online
Awesome Music: The game really isn't one for music, but there are several competitors, such as this and this.
Demonic Spiders: While Your Mileage May Vary, most players have reached the consensus that Flanaes (essentially sentient flowers) are among the most annoying enemies in the game.
Goddamned Bats: The aforementioned Flanaes qualify, but there are also other enemies that attack one on sight, considered to be these amongst some. Standing amongst this class are the Woopie Gluttons (giant wolves), Pomic Generals (giant ant people) and Rackie Hooligans (maul-wielding raccoons).
Nightmare Fuel: The Desert of the Dead can qualify to some. Well it is effectively a place where the unlucky dead are shackled to with nothing but the remains of their past to keep them company...
Tear Jerker: In order to travel to the planet of Luna (Level 70+ only), players must find a doll and quill to help the ship get off the ground. This might sound silly until you learn the reason behind it... It turns out that the quill belonged to the inventor of the ship, until he was killed by Krawfies. The little girl was his daughter, who was always so ill she could barely move. she dreamed, however, of flying amongst the stars listening to the Sonnet of the Galaxy. This never came to be, as she died before the ship was complete. But her doll can still fly around the galaxy in her stead, so this is why the doll must be found. Powerful stuff...