OK, so I guess I could probably do without the "ethical conundrums," when I'm trying to have fun, but having played the demo, I can confidently say that Bioshock is easily one of the most amazing looking games I've seen to date on the XBOX 360. It really is like Myst, only you have complete freedom of movement. Oh, yeah, and you have bioenhanced zombies trying to kill you. Oh...right, and you can also shoot fireballs. But apart from that it's just like Myst...really.
As the sole survivor of a plane crash over the Atlantic, you find yourself stranded inside a massive underwater city called Rapture. Imagine if Ayn Rand were a mad scientist, and had created an objectivist paradise while selling addictive bioenhancement drugs to the public, causing the entire population to develop superhuman powers, then go insane.
You come in after things have gone off the rails in Rapture, with zero information about what happened. BioShock's subtle storytelling techniques feed you little bits of the back story, mostly through voiceovers on your radio and audio diaries you find lying around the carnage. Seeing a pair of corpses intertwined on a mattress with a spilled bottle of pills next to them is one thing; hearing their final moments on tape is quite another.
BioShock isn't just an example of how to craft an intelligent game narrative. It's also an excellent first-person shooter with perfect responsive control and a wide array of weapons, all of which are upgradeable and use different types of ammunition. And you've also got those ever-present biochemical enhancements at your disposal, from the relatively mundane (fireballs, telekinesis) to the truly freakish (a swarm of insects that unleashes from your left forearm).
Definitely not one for the kiddies...but it's really something to behold. If you're a fan of FPSs, you're going to want this one.