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: Phantasy Star Online
Complacent Gaming Syndrome: You will rarely find anyone doing anything other than playing the Boss Rush quest "Towards the Future" over and over again, as it's the fastest way to gain experience, and the easiest way to farm a particular boss for their rare drop.
Crowning Music of Awesome: Sonic Team is behind this game, so it's a given. Not only that, but an unofficial "Premium Edition" for Part 2's soundtrack was done by some of the biggest musicians in video game music because it was that awesome.
The Spread Needle, which is either one of the most loved or most hated weapons in the game. Which one it is depends on whether or not you had one. As a weapon with the range of a mechgun but with the capability of hitting up to five enemies at once and firing speed of a rifle, it can clear out entire rooms of enemies, even on higher difficulty levels, in absolutely no time at all, and could be used by any non-Force class, even Hunters that had no business wielding one (though this was changed in later versions of the game to allow only Rangers to use it). The reason it's so hated is because the game's experience system would only grant shared experience for a kill if a player actually hit the enemy. Since Spread Needles could (and often did) clear out entire rooms before anyone had even a chance to get a hit off, the result would often be the guy with the Spread Needle getting ALL of the experience. Needless to say, pulling out a Spread Needle is a very good way to make enemies. While it was nerfed for the Gamecube release on (and hard, only being about half as powerful as before), it remains a very dominant weapon.
The Yasminkov 9000M. It's a pair of Mechguns that have the range of a rifle, meaning you can hit an enemy from across the room nine times with a weapon that's still more powerful than most Mechguns.
The Frozen Shooter has a near 100% chance of freezing enemies. As such, even the most dangerous non-boss enemy is rendered completely harmless.
Good Bad Bugs: Going back to town via telepipe and returning respawns monsters instead of storing them. This means that each time you telepipe, monsters with a rare variant have a new chance to be spawned as that rare variant. Farming for certain rare items becomes a lot easier and faster. This only works offline, though.
Narm: In the quest, Seat of the Heart, Elly Person's insistence that Calus is "human" can seem like this for a few people, especially those who are more pragmatic.
Nightmare Fuel: The final boss starts off in an open meadow with an obelisk. Once you get near it, look at the floor.
Tear Jerker: The ending of Episode I, and the realization that you just killed Rico. That, and the fact that you were minutes behind her the entire time.
That One Boss: A majority of the bosses are rather tricky, but some stand out:
Episode 1 had De Rol Le, who gives Hunters and Casts hell and has a strong attack that strikes the platform you're on at random in the dark. There's also Vol Opt, who will occasionally raise a series of blue lit pillars from the floor, along with a lone red lit pillar. Landing an initial strike on any of the blue pillars will prompt an immediate and often lethal (or, if you survive, debilitating) attack on the party, and has an array of very strong attacks in his second form. And then there is Dark Falz, whose attack are extremely strong, some being undodgeable.
Episode 3 has the Leukon Knight (whose everchanging stats are rather annoying), Pollux (for the Hunters, constant AP gain, an immunity to weak attacks, and a timed ability where she starts ignoring your weapons to hit you directly), Castor (for the Arkz, very powerful long range attacks, dice roll effects are instant-kill on your monsters 65% of the time, and able to damage you by killing your monsters) & Amplum Umbra (who just throws the rules right out the window).