Beautiful and Bone-Chilling
Bioshock is probably one of the most disturbingly beautiful games I've ever played. While the aesthetic is clearly designed to make the player uncomfortable, it's clear that the game's designers took great care to construct a believable world. The environments are believable and look lived in, water effects are above par, and the dynamic light and shadows really add to the sense of dread that makes a really good suspense/horror game possible.
The other half of making the world believable is giving it a compelling story. Rapture has no shortage of interesting characters, and the audio diaries that litter its halls add a wonderfully woven back story to an already intriguing world. Bioshock is a shining example of how to properly tell a story in a first-person shooter.
The game's controls are solid, its weapons varied, and a veritable host of power-up combinations make for an experience that never gets dull. Plasmids, or genetic enhancements, provide a new implementation of on old mechanic, namely spellcasting, but supported by an impressive customization system and a drool-worthy physics engine.
While Bioshock leaves very little to be found wanting, it's not without its problems, minor as they may be.
While Bioshock's layout is generally good at helping the player suspend disbelief, there are times when the age-old "invisible wall" problem comes into play. Certain ledges, staircases, etc that look as if they should be accessible are instead impassible borders. The game does avoid this for the most part, but it cropped up enough that I felt it bears mentioning at least.
I also had some issues with the controller mapping, particularly certain buttons performing double duty. For example, the x button is used to hack machinery, and in many cases you need to do this quick, before a turret or security bot is reactivated. This isn't a problem, except that x ALSO is the hotkeyed button for using an EVE hypo, so if you hit it too early you can end up wasting a valuable resource. The same thing happened to me occasionally with using the b button to cancel out of menus and accidentally using health packs.
All in all though, most of my issues with the game were minimal and didn't take away at all from the overall experience.
The Bottom Line
Imagine being totally immersed in a world where everyone around you has gone horribly insane and you are the only sane person left. Not a new concept, but entirely re imagined and relocated to Rapture, the underwater utopia gone wrong.
Bioshock is chock full of truly frightening moments, and not the standard spring-loaded cat stuff, but real glimpses into chaos and insanity. There's nothing about the game that isn't entirely creepy, but at the same time appealing.