If Metroid and Resident Evil had a baby, it would be called Bioshock.
Rapture is beautiful and detailed place full of a rich, dark atmosphere. Great care was delved in little details to fill the world with so much turmoil. A funeral parlor with somber music, a gentlemen's club, even a liquor store are all places that you can explore (and raid). Rapture is a magnificent piece of art that should be adored.
Combat consists of several guns that you pick up throughout the game along with a unique "magic" system called plasmids. Plasmids are genetic materials that enable you to light people on fire, send a swarm of bees or simple pick up objects with telekinesis and hurl them at your enemies. The guns are all basic weapons, a pistol, a shotgun, a rocket launcher, a machine gun, and even a crossbow to name a few. There is only one melee weapon, a wrench that you get early on but find yourself seldom using it as you will have gain stronger weapons. Some weapons are difficult to use as there is a kickback that forces you out of the line of sight of your enemies. This can cause you to waste precious ammo as they are limited and they disappear fast.
As you collect plasmids, you also collect tonics that can help you with your powers and/or defense. They can help you with your hacking abilities and earning more points on research. Hacking vending machines and safes require a mini-game with a pipedream feel to it. You are given a certain amount of time to complete the hack but if you fail, it short-circuits, causes damage to you and then you have to try it again. As the game progresses, it will become more difficult to handle, sometimes impossible to finish. Luckily, you will have automatic hacking tools or if you have the cash, a buyout hack. Research just involves taking pictures of the enemies that you come across throughout the game. This is essential as there are levels of research to attain that will give you bonuses in damage dealing to the enemies that you took the picture of. Once you get a camera, starting clicking away as you will always have an abundant of film.
I personally didn't care for story that everyone is raving about. You should only really care how such a prosperous city can be turn into total ruin. The protagonist you control, Jack never says a word and most of the objectives given are told through Atlas, a talking box in the corner of your screen. The plot twist made no concern to me as I was more into exploring the world of Rapture and collecting power-ups a la Metroid style. The Resident Evil style comes in as throughout the game, blood and guts along with disgusting and disturbing enemies follow you at every turn. And there is lots of blood. Big Daddy's are bosses in there own accord. The first time I challenged one, I died like 20 times so its best to deal with them later in the game, preferably after you attain a rocket launcher and the camera. They are touch because most of your weapons will hardly do damage and they never stop them in their tracks. Don't be surprise to be tossed around like a piñata when you take one on.
My time spent in Rapture is a memorable one. There were only minor nuances that my have prevented me to like it more but they are trivial of the sheer scope of the game. If you're thinking of picking up a first-person-shooter different then the normal Halo or COD, then Bioshock is perfect for you.