In one of the scenes in Case West it's revealed how Phenotrans constantly get their supply of zombies. Let's just say that if you ever thought listening to the news and hearing about all the people gone missing and how they never came back was horrible, wait until you get a load of this... Also doubles as a Tear Jerker.
The zombies eventually get mutated by a gas. These Gas Zombies will literally chase after you, sometimes in groups. Their frighting battle cries don't make things better, either. Good luck dealing with them!
They're also pretty big Demonic Spiders. If a normal zombie gets a hold of you its easy to shake it off with a button command or a couple twists of the analog stick, but being grabbed by a gas zombie means you have to do a whole mini quick time event to get the bastard off. As if that wasn't bad enough, they can also stun Chuck by making him cough and chase after him at a pretty fast pace. Oh, and they attack in GROUPS. Still, all of that is nothing compared to their introduction scene where they kill a group of soldiers in really gruesome ways. The first gas zombie vomits acid blood on a nearby trooper who falls to the ground begging for help while his buddy is snuck up on by another gas zombie. After that they all get picked off one by one as the monsters surround them. By the end of the "fight" the only survivor is their commander, who escapes by getting into a nearby vehicle and driving off. Yes, these things are SCARY.
In DR 2: OTR there's Sandbox Mode where the player is free to do whatever their hearts desire, and challenges in case the player gets bored of killing 100000 zombies for an achievement or Protoman's suit. One challenge that the player can unlock is Rooftop Massacre Pt. 2, which is on top of the safehouse in Fortune City. And if you didn't guess from where this is going, or why there's only one gas zombie on the roof, get ready for when you attempt the challenge. You have to kill masses of gas zombies. And guess what. They don't despawn once the challenge's over.
Brandon Whittaker. Let's count the ways this guy is the scariest hippy since Manson: He's covered in blood, the bathroom he's holed up in is bathed in a green light which turns that blood black, he fauns over the "beauty" of Chuck and CURE's "plan," and just before the boss fight where he uses toilet stalls to teleport and repeatedly licks a shard of broken glass as a taunt? Oh yeah, THAT SMILE.
If you think he's bad in the main game you might not wanna pick up "Off The Record" any time soon. He is directly behind the outbreak this time and unlike Chuck's version you can't do ANYTHING to save the survivor he's captured. He actually begins the fight by slitting her throat with a shard of broken glass... and then he comes after you with it! Oh, and don't worry, he has been officially promoted to storyline boss, you HAVE to fight him sooner or later... sweet dreams.
If seeing what could've happened if Chuck had failed to find Zombrex for Katey in Off the Record doesn't cause you to break down in tears, it might just make it hard for you to sleep.
Who says you need "Off The Record" for that? If you don't bring Katey any zombrex in the main game they actually turn her into a zombie, complete with a brief cutscene of a horrified Stacy watching her turn. Then, to really twist the knife after stabbing the player right in the heart you get another cutscene as soon as Chuck gets back to the saferoom. This is one of the few times he shows any emotion in his voice and makes it clear just how bad you screwed up. THEN, just in case you didn't feel bad enough, Chuck basically commits suicide over his despair at losing Katey. Goddamn, Dead Rising...
Some Foreshadowing in play during the initial outbreak: Frank can enter Chuck's room (where Katey would have to be rescued in the original Dead Rising 2), where he can see a shitload of blood, with Katey's personal effects scattered around it. This kinda plays into effect when Frank encounters Psycho Chuck. To quote Mr. West:
You can even take a pic of the bloodstains, You Bastard. Granted, it disappears after the outbreak, but still...
Randy Tugman. A morbidly obese man with a chainsaw that kidnapped and murdered women when they didn't pass his criteria as a potential bride. Oh, and he only wanted to get married so that he could finally lose his virginity. He waited for the zombie apocalypse to try this. When Chuck or Frank confront him, Randy casually murders his preacher dad, too.
"Left Hand" Lance in one of the Tape It Or Die blogs even calls Slappy this, word-for-word. Maybe he's One of Us?
On the subject of jump-scares, in Off The Record you can have three survivors following you and you are escorting them to the safehouse. There is a zombie lying on the ground outside. You go by the saying 'better safe than sorry' and shoot it. You go past the maintenance room and proceed to go down the stairs, when all of a sudden some zombie you didn't see playing dead grabs onto your leg while a FUCKING SCARE NOTE BLASTS FROM YOUR SPEAKERS! The scary part about this is that it can happen at any time! Even those who play it safe will fall for it sooner or later...
Antoine the chef. He lures survivors of the outbreak into his restaurant so he can cut them up and eat them and during the fight will actually try to shove some of his food down your throat. It gets even worse when Fridge Horror sits in and you wonder just how long he has been working at Fortune City...
How about his death? Just imagine how it would feel to drown in a boiling-hot fryer.
Not only do you realize what he has made the meat out of, sometimes he will call you bacon. And it does not help one bit that there is some spoiled 'bacon' in a box near where the kidnapped chick is held captive. This is scary for several reasons because a) You can eat it... (shudder) b) IT'S FUCKING HUMAN MEAT! c) Who knows kind of human it was made out of? It could be zombie meat. (Antoine doesn't follow Larry's way of choosing meat in the first Dead Rising). Zombie meat probably would work the same for Antoine. c) Antoine said it tasted like chicken!
Late in the game, if you completed the case files, the safehouse gets breached, zombies flooding what was up until that moment a safe space. Not helping matters at all is the fact that it was an act of sabotage.
Ending S. It starts off pretty nice with Chuck, Katey, and Stacey leaving Fortune city after Chuck has killed TK. Then, for no apparent reason, a zombie jumps into the frame and roars like a maniac. To quote a popular YouTube comment: