Nightmare Fuel / Mega Man Battle Network

• As a result of Net Society, lost or abandoned items dip into existential horror for the Mr. Progs inside of them. While instances pop up multiple times throughout the series, Battle Network 5 features this perhaps the most prominently with Oran Isle, an mining island that has long since been vacated by most of its occupants. As a result, most of the Mr. Progs within the computers for the mining equipment typically are reduced to lamenting how lonely they are or wondering where everyone has gone.
• The Power Plant dungeon has all sorts of this. The viruses are tough, Mega's healing abilities are crippled, and there are dozens of broken Programs that attack you and behave as viruses. Remember, Programs are sentient beings, so breaking them results in a clearly unpleasant Face–Monster Turn.
  • It should be noted that one of the first ones you meet denies being "altered", which suggests that some asshole (ElecMan, most likely) has been tampering with them and has turned them into mind-broken suicide machines. And the worst thing is, unless you have the ability to escape combat, you're going to need to destroy each one you come across, because broken programs are some of the most dangerous viruses in the dungeon, continually encroaching on your area and brandishing powerful electric shocks. These poor guys are essentially victims of Mind Rape that Mega has to Mercy Kill. What Do You Mean, It's for Kids??!
  • Though it becomes a bit of Nightmare Retardant later on when one of them quotes "All your base are belong to us" word for word.
• Lan and Mega entering Yum Square. For reference, Yumland (read: Cyber-Thailand) is supposed to have the world's largest population of NetNavis. As they travel through Yumland's Cyberworld, Lan and Mega are confronted by a notable lack of this population, which becomes painfully obvious when they come to the Square, which is desolate and silent. Mega must walk, alone, through the creepy emptiness, past unattended store counters, following the sound of clicking and clattering, where they find the sole surviving NetNavi who informs them that his entire population has just been murdered.
  • It gets a whole lot creepier when you're forced to break into the desolated area's vault in order for Mega to achieve Style Change, triggering the security system that keeps attacking you as you make your way to the exit. You're technically robbing the website of the last thing it had.
• Battle Network 2 features the Quiz King, a ghost who is possessing the body of an elderly man that cannot pass on to the afterlife until his quiz is completed. Once Lan is successful at answering all 15 of his questions and letting his soul pass on, the man the Quiz King was inhabiting admits that he has no recollection of his life since he was 13-years-old.
• Battle Network 3: the attack on Sci Lab. Frankly, it's one of the more realistic depictions of both hacking and terrorism in the series, which makes it particularly nasty, but the fact that YOU enabled this is probably the worst part.
• The scene where Mamoru nearly dies as a result of a WWW attack on a hospital to steal vital data is pretty nightmarish in a mundane way.
  • This becomes even worse when you consider Black Hat hackers in real life can infect a hospital's systems with ransomware to achieve basically the same thing.
• With Alpha in the hands of the WWW and rearing to destroy the internet, most of the net in general is drained of its vibrant colors — most places look significantly dull, as if Alpha drained away a good portion of its life.
• Battle Network 4: It's a small one, but seeing Dr. Regal destroy the platform Lan was on and Lan just barely escaping death as the platform he was on falls offscreen, coupled with the explosion sound is unsettling.
• Also from 4, the Hikaris' doghouse alarm finally goes off. Somebody's broken into their home. Lan rushes home, nobody's there. He runs upstairs to his room, and finds his mother, Bound and Gagged in the corner of his room. On his computer is a note taunting him about doing much worse. And then you realize there wasn't enough time for the intruder to act if you assume the alarm went off when he broke in, so the implication is that he broke in quietly, went after Haruka, left a note, and then deliberately triggered the alarm to get attention.
• If you perform poorly and MegaMan enters an Anxious state, the next time you open your Custom Screen, the Dark Chips are immediately highlighted, patiently tempting you to use them as the battle music is slightly muffled by a faint pulsating sound. If you succumb to temptation and use it, MegaMan's Emotion Window reflects his corrupted self with a Psychotic Smirk. If you use enough Dark Chips over a playthrough, you can begin the battle in this state, showing the corruption has completely consumed MegaMan.
• Nebula Grey from 5, the literal embodiment of human sin, anger, hatred, and all of its dark impulses. Holy fuck. Regal's plan for it is to basically have it corrupt the entirety of humanity into being as misanthropic as he is. Might be even worse in the manga, where we see it unleash much more devastation and almost destroy every character who tries to defeat it.
• CircusMan in Battle Network 6, who is literally a life-stealing Monster Clown. He has an attack that the fanbase infamously nicknames as the "Tent Rape Attack". If that isn't bad enough, the first time you see him, you witness him opening his chest to reveal a vacuum, which he uses to absorb and capture one of the two Cybeasts. If that still isn't enough for you, he also successfully uses it on MegaMan later! He's basically Kirby, without the power transformation part and hundreds of times creepier.
• Lan and Mega Man get into all sorts of extremely life-threatening situations to save the world. simply because they're the only ones who can in a world of incompetent authorities who are unable to handle them. This includes taking thousands of times the normal amount of electromagnetic radiation, nearly having their souls sucked out, fighting a literal god, taking down the embodiment of human sin, and escaping half a dozen exploding bases when they should be hanging out with their friends and doing their homework. One can only imagine how their parents feel about the whole mess...
  • Lan's father, grandfather, and identical twin all have the same genetic heart condition. It's never actually mentioned, but presumably Lan himself and his son Patch from the epilogue have it, too.
• The game over screen can be a startling appearance the first time. When MegaMan's health is reduced to 0, he fades out of existence and the text "MEGAMAN DELETED" appears. Since there is no "extra lives" system in this series, it cuts to a screen with the text "GAME OVER" immediately afterwards. The screen in 4-6 is downright creepy, with a more solemn jingle playing over golden text with a pale red background and fast-moving blocks of data.