Doom 3 (PC, Xbox) | Mars City/Mars City Underground
A leisurely saunter through the UAC base lets you casually get attached to the game world, before the thick sense of impending disaster explodes in the most horribly visceral way imaginable. You’re suddenly alone in a dark and noisy world of fear and confusion. The people you met earlier are dead, dying, and torn to pieces. Wrecked doors block your path, but reveal enough to show you glimpses of something utterly foul on the other side. Broken screams and prayers crackle over a failing comm system as the whole world is irretrievably torn apart and the building shakes to pieces around you. You’re drenched in the feeling of hopelessly drowning in evil usually reserved for nightmares, and things have only just begun. It’s the best ghost train ever made.
Ecco the Dolphin: Defender of the Future (Dreamcast, PS2) | Hanging Waters
If you were one of the many who turned up their noses at this slightly New Age-y (OK, really New Age-y) dolphin adventure, you missed out. You didn't guide a baby whale back to its mother, swim away in terror from a giant Great White shark or outwit a massive crocodile in a stalactite-filled underwater cavern. You also didn't get to see the Hanging Waters level, which - aside from Soul Calibur - was one of the Dreamcast era's most jaw-dropping technical achievements.
Part of Ecco's adventure takes place in an alternate future, in which the world has been conquered by evil dolphins (only when we actually write that do we realize how stupid it sounds). And what do dolphins do when they rule the world? Set their energies toward creating insane, dangerous aerial waterways for no good goddamn reason, or course! Forget about being surrounded by dependably omnipresent water - Hanging Waters pitches you through rollercoaster-like tubes of flowing water suspended only by anti-gravity, meaning it's entirely possible to leap out the top of a "tube" or fall out of its bottom, if you're not careful.
But navigating the aquatubes is worth the risk, as it's all very stunningly pretty, and it lets you take in a breathtaking view of the tropical mountain that all these suspended waterways snake around. You can glimpse it for yourself right here (although you might want to skip to around 0:30 to bypass all the loading and menu nonsense):
