Here's another one you can experience all by your lonesome. Acid-trip shooter Rez barely registers as a game to some, but its trance-like blasting has nevertheless ensnared a large following. If the swirling colors and slowly evolving, humanoid spaceship aren't enough to freak you out, try cranking the speakers.
Above: Doesn't really make sense, but it doesn't have to. Just listen
As with Silent Hill, you need all the lights off. Pull the drapes, tape off the door frame, whatever you gotta do to make sure Rez is the only thing you see. Then, max out whatever sound system you have and wait for your brain to ooze out of your nose. At some point you'll either go totally insane, or begin to believe that you can actually see music. For bonus points, you could always grab the Trance Vibrator and boost the PS2's Dual Shock, rhythmic bass effect to points of absurdity.