* ComplacentGamingSyndrome: You will rarely find anyone doing anything other than playing the BossRush 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.
* CrowningMusicOfAwesome: 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.
** [[http://youtu.be/YI_IGFBOTHE Tower of Caelum]] from Phantasy Star Online Episode 3
* DemonicSpiders: The game had tonnes in Ultimate Difficulty:
** Ob Lillies. They spawn in large numbers and spit an instant death spell. Oh, and they use an undodgeable paralysis area attack when damaged.
** Sinnows, of all flavours. Combined strong attacks with buffs, heal spells, TeleportSpam, invisibility, and/or freeze attacks. Even worse, thanks to their [[DynamicEntry hideously damaging leap attacks]], Forces and Rangers can't fight them effectively at range.
** Garanz/Baranz: Basically MacrossMissileMassacre in enemy form. When playing online, without the benefit of MercyInvincibility, every attack from these things is basically an undodgeable OneHitKill. Facing two in a single room virtually requires someone in the party who can freeze; three or more virtually guarantees at least one player death and at least a 50% chance of a total party kill. Arguably the most dangerous enemy in the game (online, at least...)
** Chaos Bringer/Dark Bringer: Lots of HP, hard-hitting attacks, a brutal [[DynamicEntry charge attack]], and reacts to being hit by draining your TP, then using it to blast you with a horribly strong ranged attack.
** Indi Belras: Fast, hard-hitting ranged attacks with unlimited range, immunity to flinching, and the ability to paralyze in close.
** All of the Episode II mini-bosses to a degree, but the Mericarol/Merickle/Mericius enemies take the cake. At range they spit out an unblockable OneHitKill orb (and, unlike other OneHitKill methods in the series, it isn't based on Dark tech, so raising EDK does nothing). In close it would swipe at you with its claws and if you hit back, it would unleash ''another'' OneHitKill attack that took out anything in contact with it. Virtually the only way to kill it without dying involved freezing it.
** Ill Gills. They're faster than you, they can root you to the ground, and their scythes will absolutely destroy you (and, of course, they have a OneHitKill attack, because why not?)
** The Seabed is pretty much inhabited only by DemonicSpiders [[MyFriendsAndZoidberg and Recoboxes]]. To whit, we have:
*** The Delbiter: Strong, fast, attacks up close and at range, will [[DynamicEntry charge at you if given the slightest provocation]], can confuse with its scream.
*** Morphos: Invincible from the front, shoots a beam that is all but guaranteed to knock the player down and pin them in place
*** Deldepth: Races around the floor impossibly fast (during which time it's invincible), and will rise up only to spit (say it with me) OneHitKill attacks (or toss the occasional freeze bomb).
* FridgeHorror: Anyone wounded by a creature with the D-Cell Virus eventually becomes corrupted by Dark Falz and turns into one of his horrific minions, as the Beta-772 logs [[spoiler: and both Red Ring Rico and Heathcliff Flowen]] can attest. De Rol Le even has some tentacles on its back that it uses to inject the virus directly into anything it runs into. The mines show that even robots and other non-organics are not immune. So... what's stopping those injuries from infecting ''you''?
* GameBreaker:
** The Spread Needle, which is either one of the most loved or [[TierInducedScrappy 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.
* GoodBadBugs: 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.
** When telepiping back to the surface, your character would take a moment to spawn and, during that time, you could move very slightly through obstacles. Repeatedly piping back and forth allows the player to slowly inch their way through impassable walls in some quests, accessing areas that were [[DummiedOut not meant to be present in the final game.]] One area is filled to the brim with slimes, which is nice because they don't spawn in appreciable numbers anywhere else.
* LootDrama: Combine PowerEqualsRarity with stupidly low loot drops for some of the best gear and watch the sparks fly when a red box appears.
* {{Narm}}: In the quest, ''Seat of the Heart'', [[spoiler: Elly Person's insistence that Calus is "human"]] can seem like this for a few people, especially those who are more pragmatic.
* NightmareFuel: The final boss starts off in an open meadow with an obelisk. Once you get near it, look at the floor.
* TearJerker: The ending of ''Episode I'', and the realization [[spoiler:that you just killed Rico]]. That, and [[spoiler:the fact that you were ''minutes'' behind her the entire time.]]
* ThatOneBoss: 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.
*** Dark Falz's third form was a nightmare for android players, particularly [=HUcasts=] and [=HUcaseals=]. He [[TeleportSpam jumps around the arena]], rarely sticking in melee range for long, and flickers between semi-invulnerability (he's still vulnerable to techs - which androids don't have - and weapon specials) and vulnerability every 5 seconds or so. Since android hunters lack any weapon that has a range longer than a handgun (and aren't particularly accurate with ranged weapons either), this made damaging him extremely difficult. Add into this that Dark Falz is a MarathonBoss and androids have limited capability to heal themselves, and it basically meant that androids often had to be 5-10 levels higher than anyone else before they could solo Falz and move onto the next difficulty.
** 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).