The NightmareFuel page for PhantasyStarOnline.
* The loneliness of the areas can get to you; aside from monsters or NPC escort missions, you're the only one there.
* Dark Falz. "Hey we finally beat the game! Good job gu--WHAT THE HELL IS GOING ON!?"
** When you enter the Dark Falz's lair, all you see is a pretty blue sky and green grass. It seems you have beaten the game and about to collect your spoils, but no, the sky turns black and the nice green grass warps itself to tiles of screaming faces. Then Falz shows up. . .
*** Oh ''hell'', '''everything''' about Dark Falz is pure, concentrated nightmare. If the above notes hadn't convinced you already, let's take a closer look, shall we? [[spoiler: Dark Falz is found sealed in a space ship. And yet the last two floors [[WombLevel look like the innards of some giant monster complete with pulsing, squishy organs, weird, gigantic yellow/orange blood cells floating in you're-best-not-asking-what, and loogies plastered as far as the eye can see shaped like spider webs.]] When you finally meet him, you are greeted with the sight of a monstrously mutated humanoid thing that shoots little spikey things that come after you and has powerful techs that get ''even worse'' for every new form he takes.
** And if you didn't already pick up from the hints ''before'' you face Falz... Falz can infect another living creature and infect them beyond recognition to the most hideous abominations capable of making [[VideoGame/ResidentEvil3Nemesis Nemesis]] look as cute and cuddly as a puppy. Rico charged into battle before you did, so take a wild guess what happened to her. Really, guess. What's more,[[SarcasmMode as an added bundle of fun,]] Dark Falz doesn't have to do ''anything'' to infect you [[spoiler: even while he's already infecting something else as his body]], because just coming in contact with his hordes of spikey mooks and getting reckless enough to be scratched by them is enough to start the fun. And by "spikey mooks" I mean the ''hordes and hordes of spikey goodness that swarms you the minute you get anywhere near his precious obelisk''. Good thing [[GameplayAndStorySegregation you are just too awesome to be affected by any of Falz's infections]], because in Episode II you'll see someone ''else'' who wasn't so blessed, and promptly got infected. [[spoiler: You even get to personally meet him later on, and although he ''did'' get the added boost of being combined with an AI and his dark-energy-based sword, just imagine that ''that ''could've been '''''you''''' had the [[GameplayAndStorySegregation game and story segregation gods]] not loved you enough.]]
*** And just in case you didn't notice, your battleground is '''covered in twisted faces, writhing in agony.'''
*** Just to add to the atmosphere, oh god, the music. The first thing you hear when you warp to the field is [[http://www.youtube.com/watch?v=ZD0kqNGvjrI The Nearest Place to Heaven]]. Well, hey! This is kinda nice. Little piano music and birds...why are the birds obviously looping? Must be a lazy track editor...is...is it making a noise? Like a...hazy sorta, distorted noise in the background? And then all the eeriness just adds up over each other and you start to feel real uneasy. Just go near that obelisk and--'''[[http://www.youtube.com/watch?v=_Yz1tTp0SHU&NR=1 oh dear god, what the hell is going on]]'''. When did I start playing SilentHill?! W-what are these things?! Why is the music crying at me? [[http://www.youtube.com/watch?v=D1gTkJgsF4c&NR=1 Then Dark Falz shows up.]] The music transitions wonderfully into a grungy sort of techno perfect for a final boss. But it's okay, you beat it! Let's tackle Hard Mode. Ha, beat him agai-- [[http://www.youtube.com/watch?v=GAFVrBqUtLw&NR=1 what is this, I don't even.]] You finally realize this just isn't a big monster; that music? That look? You are fighting a '''''god'''''. The tracks in all just work wonderfully at emulating exactly what you're all ready feeling.
* The Seabed in Episode II and the ApocalypticLog contained within. As you move through the dungeon, the logs cover the [[BodyHorror mutation and corruption]] of [[spoiler: Heathcliff Flowen.]] Then, you encounter a log entry that's just heavy static interspersed with rambling nonsense. Only the next time you get to speak to your NPC guide, she nervously informs you [[spoiler: that it wasn't a recording; it was a transmission from elsewhere in the facility.]]
** Just the name of the final boss arena is somehow disturbing on a very subtle level: [[spoiler: Test Subject Disposal Area.]]
** [[HellIsThatNoise The noises Olga Flow makes when you first enter the boss area are disturbing in the extreme.]]
* In Episode III, it's revealed that [[spoiler: the players really ''are'' beating Dark Falz and Olga Flow over and over again, with them getting stronger each time, and eventually strong enough to break free of their confines and destroy everything with no one capable of stopping them]].
* Anyone who's played ''VideoGame/PhantasyStarOnline2'' need only hear three words before they start freaking out. '''''EMERGENCY CODE: AVOID'''''.
** To clarify: When the Avoid Code triggers, you're left with no choice but to run from a flying EldritchAbomination called a Gel Wulff that can only be described as a giant, ghostly pitcher plant with bat wings. The creature is completely unkillalbe, can move faster in a straight line then the players, and can effortlessly pass through walls. It's only purpose is to hunt down the player characters one by one, and will not stop until it succeeds, or the Avoid Code's timer runs out. It also hits like an unholy eighteen wheeler, two-shotting or possibly even one-shotting a player.
*** Updates have, thankfully, mitigated the nightmare factor of this Emergency Code: the time limit for the Code has been shortened, and the monsters can now be killed with charged photon turrets.
** Official service recently added in Visbolts, blasts of red lightning that can appear out of freaking nowhere and have a fairly-sized AOE. You constantly have to run around to avoid them, which can easier said than done if you're hanging around with a full party or three, as there can be multiple targets for the Visbolts at once.
** Something that's also been around for a while is ''Emergency Code: Destruction'' that spawns a bomb called a Baize. It starts off as a tiny ball composed of D-Arker veins, but it very, ''very'' quickly grows to massive size and eventually explodes. Failing to destroy it in time - which is hard, because it's ''durable'' - will cover the affected area in a red hue while some evil version of AcidRain pours down and drains the health of anything there like mad; it doesn't last forever, but still for a while. If you don't think you can destroy it in time, get the ''hell'' out of the area.
* In ''Online 2'', [[spoiler:Dark Falz is back. Again]].