Has an MMO ever made you afraid? Have you ever been truly scared of what might happen next, of what might be round the next corner?
I love the Stratholme and Scholomance instances in World of Warcraft. The former is a ravaged, ruined city, home to hordes of the Undead Scourge, and a small but fanatical cult of insane ex-Paladins. The buildings which line the street are smashed and burned; they lean at precarious angles, with fire still licking hungrily at their walls – what few remaining signs there are outside the houses remind you that people once lived here, before Prince Arthas Menthil slaughtered them.
The Scholomance instance is a sprawling journey through the catacombs of a dark castle in the middle of a dead, poisoned lake – a place given over to the instruction and Necromancy and the Dark Arts. It's based on an old Transylvanian folk tale, and features the spirits of dead servants of the previous masters of the castle, tortured to death by the sadistic scholars within. As you run through its corridors and vaults, you come across the remains of people, perhaps innocents used as fodder for lessons, perhaps students executed as examples.
Both instances are two of my favourite in the entire game. Given the opportunity, I'll still run through them now. Not only are they technically well designed, but the lore behind them is excellent, hinting at the fate that befalls the innocents in WoW, the peons, farmers and sundry other NPCs we barely glance at.