Please note: that some of the things mentioned in this guide might be considered very light spoilers. I'm not giving away any plot points and do point the way towards making some real story choices, but I deliberately stay very vague. If you want to know nothing about Rapture or the weapons and abilities you get, wait until you've played someBioShock before coming back to this guide. Bookmark it, though!
USE THE RIGHT AMMO
All of your ranged weapons in BioShock have a few types of ammo which you can load. The pistol and machine gun both include normal, Antipersonnel, and Anti-armor rounds, the latter two of which are more scarce than the regular stuff but also more specialized to killing specific foes. I recommend you keep your anti-armor rounds specifically for fighting Big Daddies with, especially earlier in the game. The shotgun has a different set of ammo: Regular, Exploding, and Electric Buck shot. Unfortunately I found that as you go through the game, the shotgun - even when upgraded - isn't quite as useful as I expected. I usually just would leave Electric ammo in there for a quick stun on a Big Daddy or to take out a security camera I didn't feel like hacking.
Later weapons have some wacky ammo, most of which is limited in use by just what enemies are weak towards what. Feeding a ton of Liquid Nitrogen at a Splicer doesn't help much, but some Napalm does pretty well - just be ready for long reload times and a huge thing blocking your view when using the Chemical Launcher. The Crossbow is very powerful, but you'll really need some good aim with your gamepad or mouse to make it worth using. If aim is not one of your strong suits, then put your efforts into setting up traps with Trap Bolts to take people out ahead of time.
DEALING WITH SCARCITY TONICS
One thing you'll find out quickly in BioShock is that you can't just have a favorite weapon or Plasmid to stick with for most of the game. You're going to run out of ammo or Eve hypos eventually, and your money only goes so far in replenishing them at Circus of Values machines. It's much smarter to balance out your style at the beginning of the game by using Plasmids as well as all your weapons and ammo types, along with some healthy use of the Wrench - yes, the Wrench (more on that later). The side effect is that you'll figure out what weapons and ammo work best.
One of the best ways to increase your combat abilities is by choosing the right tonics. You can make yourself a stealthy, wrench-swinging madman who beans Splicers over the head without being seen, or you can make yourself a master magician with pumped-up Plasmid usage. Some of the game's Tonics aren't terribly useful, like the ones that give you extra Health or Eve when hacking or drinking alcohol, but most have a pretty good application.
Remember that even if you get an upgraded version of a Tonic you already had, you can still use both in different slots for a stackable effect.
Unlike most action games, your starting weapon can still be very useful even at the end of BioShock. The key to it is installing the specific Tonics that make it hit harder and faster. I wasn't a big fan of the stealth-related Tonics I grabbed, but you will find that the wrench is great since it allows you to deal with Thug, Spider, and Houdini Splicers efficiently while using no ammo.
THE RESEARCH CAMERA
Partway through BioShock, you will gain the Research Camera which allows you to take pictures of your foes - doing so repeatedly gains you damage bonuses on the enemy types you've photographed. These bonuses can be increased with relevant Tonics, too, which is a good idea to use if you're planning on getting to Level 3 research on enemies. New Tonics will even unlock just by taking pictures, so it's actually quite useful to go ahead and use the Research Camera. Remember that you can take multiple pictures of enemies for diminished research progress, and considering how cheap film for the camera is at just about any Circus of Values, it's worth taking a ton of pictures. Any picture that the game considers not good enough won't use any film either, so go wild!
If you're having trouble swapping out the camera with your real weapons or your Plasmids on the 360, remember that if you hold either bumper for a split second the game pauses and you get a quick menu for easy switching without missing a beat(down?) in combat.
As you traverse Rapture you will find special stations that give one of several upgrades to your weapons. Each of your projectile weapons has two upgrades to tack onto it, and I would recommend that you fully upgrade one gun before moving onto the next. The pistol's ammo-capacity upgrade is easily the most amusing, as it adds a miniature belt-feeder onto it to serve up 24 rounds over of a normal revolver's measly six. Those who have a tough time with the Big Daddies should snag upgrades for the Grenade Launcher, as it's easily the best weapon for quickly taking out the big guys.BioShock does do a pretty decent job of explaining this in its introduction, but do keep in mind that easy kills can be gained by using elemental Plasmids. Of course you can amplify your electricity by shocking Splicers that are in the water, but hitting oil patches with Incinerate works wonders too. Splicers that are on fire will run to water nearby to put themselves out, and that's when you can drop some electricity on them. Feel free to get creative - the game usually rewards you pretty well.
If there's one weapon I'd recommend you skip upgrading, it'd probably be the shotgun. Even upgraded, it just felt too weak even when dealing with basic Splicers later in the game. That's not to say that the Exploding and Electric buck shot isn't good, as it does have its uses, but upgrades generally seem to be better placed elsewhere.
The Vita Chamber is a checkpoint-like system that lets you respawn when you die without forcing you to load your game. Sometimes, you might want to go ahead and die rather than use a first aid kit, and in other cases you might actually want to load your game when you die instead of respawning at a Vita Chamber (especially if you were fighting a Big Daddy and can't get back to him in time before he puts a Little Sister back into one of their hiding places). Maybe you're on a tough hack and would rather die and respawn once you're done rather than loading your game repeatedly after each failure. As you go throughout the game and get into different predicaments, think about your situation and remember that the Vita Chamber is sometimes quicker than loading your game, and sometimes loading is the better idea.That hacking mini-game can really get annoying after a while, so I highly recommend you go ahead and put at least 2-3 Hacking tonics into your Engineering Tonic slots when you can. Hacking the various cameras and turrets really helps (especially for high-traffic areas where Splicers seem to respawn often), and getting into safes without paying huge amounts of cash is nice. You'll of course have to get good at the hacking game as well, as the Tonics only take you so far, so get practicing! Freezing something before you hack it will also give you extra time to work as the water will move slower. Another tip is that while hack failures do hurt your health, they won't kill you. If you don't feel like loading repeatedly on a tough hack, then just go ahead and keep trying it, going down to zero health, and either dealing with it afterwards or, if you did manage to trigger security bots with a hacking mistake, just letting them kill you. It's not so bad - that leads us to ...
USING THE VITA CHAMBER
The Vita Chamber is a checkpoint-like system that lets you respawn when you die without forcing you to load your game. Sometimes, you might want to go ahead and die rather than use a first aid kit, and in other cases you might actually want to load your game when you die instead of respawning at a Vita Chamber (especially if you were fighting a Big Daddy and can't get back to him in time before he puts a Little Sister back into one of their hiding places). Maybe you're on a tough hack and would rather die and respawn once you're done rather than loading your game repeatedly after each failure. As you go throughout the game and get into different predicaments, think about your situation and remember that the Vita Chamber is sometimes quicker than loading your game, and sometimes loading is the better idea.
TAKING ON THE SPLICERS
Headshots count! This is probably the biggest advice I can give, but I also recommend that you use Antipersonnel ammo whenever you can against Splicers. If you find that you're blowing whole 40-round magazines of Machine Gun ammo on a single Splicer, that's probably a clue that your aim could improve, but I do recommend to learn how to dodge incoming melee attacks from the Thug and Houdini Splicers and bash them with the Wrench. It's a great way to save your precious ammo for the game's tougher fights.
FUN WITH TELEKINESIS
This Plasmid is the source of some of the most fun in BioShock. You can create effective bullet shields by holding something like a trash can in front of you, or toss clutter around to take out the electrical traps strung around some rooms. It's also pretty painful to punch something heavy, even the body of something else you've killed, right into an enemy's face. Houdini Splicers are tough to fight with Telekinesis considering how fast they throw their projectiles at you, but Nitro Splicers are easy to take on with it. Overall, this is one of the more Eve-efficient Plasmids once you get good with using it, and it's definitely one of the more amusing abilities in the game at times.
If you want to get the ADAM from a Little Sister, you have to go through these guys first. They might seem impossible to take down sometimes, but it really is just that they're so resistant to certain forms of damage. First things first: anything that explodes does well against a Big Daddy. You can lay out Proximity Mines and then draw the Big Daddy right into them (just make sure you don't put the mines all on top of each other in the same spot, otherwise you will only get the damage equivalent of one explosion) or just dodge incoming attacks and dump grenades. Anti-armor ammo in the Pistol and the Machine Gun work well also. Once you get the Crossbow, using the Trap Bolts can be highly effective, but make sure that the Big Daddy doesn't send you flying back into the traps you've set out for him. The absolute best ammo to use, however, are the Heat-Seeking RPGs from the Grenade Launcher. You'll find that they do excellent damage and rarely miss, even if your own aim isn't so great.
The other type of Big Daddy is the Rosie, who dumps the daze/charge attack for a plain old rifle. This thing hurts really bad, so make sure you are firing from around corners and getting cover as much as possible. Beyond that, Rosie is a tough opponent since it's hard to shoot at something you're hiding from.One thing to note is that there are two types of Big Daddies inBioShock. The most common one is the Bouncer, who has a daze-then-charge maneuver that can be really devastating if you're not ready. They'll pound the ground, causing your vision to blur, then charge right in on you. All you've got to do is sidestep the incoming charge and you'll buy yourself a second or two of free shots. It's not much time, so stay on the ready. You can also use Telekinesis to catch incoming Proximity Mines they throw and dump them right back into the big guys' faces.
Once you've downed a Big Daddy that's protecting a Little Sister, you will have the choice to either Rescue or Harvest her. Not only do continued choices down one path or the other affect the ending you get, but you also get to choose: take 80 ADAM for a Rescue and a bonus 200 (plus some extra items/ammo) after a few rescues, or go with 160 ADAM now to go down another path and get no bonuses? If you're the kind of player that hoards ammo all the time and you don't care about which way you go in the story, you might go with the Harvest route. By the end of the game an ammo hoarder will easily be full on most kinds of ammo, so the extra perks you get from saving Little Sisters doesn't help as much as having extra ADAM. If you find yourself using way more ammo more than you do Plasmids and run low constantly, still do find the Little Sisters in every level and make sure to rescue them rather than harvest them.
HAVE FUN IN RAPTURE
If you want to check on the status of Little Sisters in a level, just pause the game with the Start button and look at the bottom of the screen. Don't worry if you seem to have progressed some and still haven't found one in a level, as you usually get a warning before leaving the area. Do note, though, that once you leave a level, you won't be coming back.
Remember that this game is not just another DOOM clone. The visuals are definitely worth ogling at, but BioShock also has an incredible story along with plenty of atmosphere that you'll miss if you fly past at top speed. Take the time to check out your environments, to learn about the many characters, both dead and alive, and really immerse yourself into Rapture. My favorite part about this game is that you can do all this and still get a great first person action experience where few compromises are made, and I hope you too can enjoy BioShock on a higher level than the more brainless titles that flood your local GameStop constantly.