With the advent of high-quality 3D graphics, it has been possible to create very engrossing, atmospheric worlds in video games. This means that some games go to great lengths to provide creepy or just downright scary levels to test a player's already itchy trigger finger and one-against-the-world paranoia. Here are a few of the most effective eerie levels from the past few years in gaming.

Ravenholm- Half Life 2

Valve's long-awaited sequel to its most popular property, the sci-fi first-person shooter Half Life, was famous before its release thanks to a new physics engine that was supposed to be so impressive that it was actually stolen in an example of real-life corporate espionage. Some years later, Valve introduced the world to the Source engine, its pride and joy gravity simulator. When Half Life 2 hit shelves, it sported a level called "Ravenholm" that served as a demonstration of Source's potential. It also happened to be an incredibly chilling example of post-apocalyptic monster hunting. The level takes place in an abandoned town that has been overrun by the very scary "head crab zombie" enemies that have since become notorious beasts in the series. Between the marauding monsters, scarce ammo and insane preacher ally, Ravenholm is one of the most genuinely creepy moments in video game history.

Ocean House- Vampire the Masquerade: Bloodlines

Around the same time Half Life 2 was released, another Source-powered game came to the PC platform. It was Troika's flawed but impressive Vtm: Bloodlines, a combination FPS/RPG set in White Wolf's popular World of Darkness. Even though players control a new initiate to the ranks of the undead, that didn't do much to make the "Ocean House" level any less scary. Set in a remote oceanside hotel outside of Los Angeles, the Ocean House is a fire-damaged deathtrap haunted by the ghosts of the family that died there a la The Shining. With no physical enemies to dispatch and plenty of unconventional surprises, the Ocean House is a lesson in survival. Players were so disturbed by the experience that the Bloodlines modding community created a patch that allowed players to skip the Ocean House mission entirely.

Valley of Defilement- Demon's Souls

In 2009, From Software released its brutally difficult action RPG Demon's Souls to much acclaim. If players managed to get far enough in the game's ruthless fantasy setting, they got treated to a particularly unsettling set of levels in a place called The Valley of Defilement. A den of disease, insanity and decay, the Valley is home to some of the most genuinely frightening set pieces in gaming. The swamps below the plague-ravaged shanty town in the Valley are home to giant slugs that fall from the ceiling and even a pit with a sickening abortion theme.

Point Lookout- Fallout 3

Bethesda Softworks' award-winning game Fallout 3 has no shortage of unsettling visuals, but there's something uniquely creepy about the Point Lookout add-on that came as the game's fourth DLC package. Like the Valley of Defilement, it's set in a deadly swamp that backs up its off-putting setting with freaky creatures and traps. Between ravenous radiation-mutated Ghouls and rock-solid inbred Creepers, Point Lookout really ups the ante for an already disturbing game.