Splicers, also known as Aggressors, are the main enemies that Jack encounters over the course of the game. The remains of Rapture's human population, they are the result of a planned attack by Fontaine on New Year's Day of 1959 to end the civil war between him and Ryan. They apparently murdered the sane population. Many of them still wear Masquerade Ball masks, and Atlas asks,
"Why do they wear those masks? Maybe there's a part of them that remembers how they used to be, how they used to look. And they're ashamed." (It could be possible some got a bathyspere working and up to the lighthouse as the last transmission of the ship The Sea Beagal said "That doesn't make sense. It shouldn't be there... do you see them? They're watching us!" "they" must means splicers)Apparently due to the biological weapons attack, they have become biologically dependent on ADAM to survive. Wandering the corridors and the tunnels of Rapture, they search for ADAM, usually in the form of Little Sisters, which often puts them at odds with their Big Daddy protectors—something that Jack can easily exploit to help him survive. Splicer possible reference to gene splicing what happened quite often during extensive plasmid usage.
BioShock
Splicers tend to wear very little armor, if any, but they have advanced physical strength and tend to be extremely aggressive in contrast to the calmer Big Daddies. They will sometimes work in groups, use plasmids and sometimes even play dead to get the advantage on the player.
Thuggish Splicer
The Thuggish Splicer attacks with blunt weapons. These can be found throughout the game and are fairly weak, but make up for it by running fast and attacking in groups whenever they can. Later on in the game the player encounters an electric version of it which makes it immune to the plasmid Electro Bolt and tonic Static Discharge, so be prepared. An easy strategy is to wait for them to lunge, then dodge and while they recover and prepare to attack again, whack them upside the head with the Wrench.
Leadhead Splicer
The Leadhead Splicer attacks with either a pistol or a machine gun. These can also be found throughout the game, but are more dangerous than the Thuggish Splicer since they can attack from a distance and will almost always hurt a bit even if they are brought down easily. These will always keep their distance from you whenever they can help it, but at very close range, they will attempt to whack you with their gun. It is worth knowing that they have to reload their guns, just like Jack. They are defenseless while doing so. They also have more health than a Thuggish Splicer causing them to be harder to take down, especially if there are more than one.
Spider Splicer
The Spider Splicer is the first Splicer you see when you arrive in Rapture, although ones you can fight are first encountered in Neptune's Bounty when you're told by Peach Wilkins to photograph three of them in order to gain access into Fontaine Fisheries. These Splicers will walk on the ceiling and throw hooks at you from afar. These hooks can be caught and tossed back with Telekinesis. When on the ground, the Spider Splicer will get near enough to physically attack you, then immediately jump onto the ceiling or backflip away and come at you from another angle. They are tough to kill due to their amazing agility. This type of Splicer is fairly hard to kill unless you obtain enough research photos to do more damage to them. Headshots and the plasmid Winter Blast are useful against these foes.
Houdini Splicer
The Houdini Splicer is first encountered when you enter Arcadia. These Splicers have the ability to teleport from one place to another in the middle of combat. They can be tracked through smoke that appears around them whenever they disappear or reappear. The more research you do on this type of Splicer, the easier it becomes to predict where it will teleport. The Houdini Splicer will most often attack by shooting balls of fire (and rarely ice), but like the Leadhead Splicer, will attack physically at close range. An easy way to track them is with Insect Swarm. If you set them on it they will follow it even if it is invisible. In combat the Houdini Splicer uses a hit a run strategy by teleporting, attacking with a fire or ice attack, and then teleporting away to repeat the cycle.
Nitro Splicer
Nitro Splicers are found rarely throughout the game; mostly in Neptune's Bounty. The first one you will encounter is in the Medical Pavilion. Your first encounter could either be at the entrance of the section where you acquire the Incinerate! plasmid, or in the Amazing Alexander's section. They will attack by throwing grenades at you from a distance. They will attack at close range, or will throw a grenade directly on the ground in order to either kamikaze, or distract you so it can escape to a farther distance. A common way of killing these is by using Telekinesis to catch its grenades and throw them back at it. Upgrades can be obtained through research that gives certain percent chances that the grenades they throw will be duds and not explode. Usually when killed they will drop a final grenade so you might want to run when you kill one!
There are ten Splicer models in the game. Their names are not revealed in-game; instead, they are associated with the sound files used for their sound bites in the game data:
- Baby Jane
- Ducky
- Breadwinner
- Waders
- Lady Smith
- Dr. Grossman
- Toasty
- Pigskin
- Rosebud
- White Splicer
BioShock 2
In BioShock 2, the Splicers return as enemies, though much weaker in comparison to their previous role in BioShock (though they have become even more monstrous than in the first game due to years of ADAM withdrawal before Big Sister's arrival)—more than likely because the player will be a Big Daddy. Notably is their limbs have become far more lanky and in some cases their faces have conformed to the shape of their masks. However, according to a recent Xbox magazine article there is an even more powerful and monsterous kind of Splicer that is capable of taking a Big Daddy out. Also, in an interview on Gametrailers.com with Jordon Thomas, he mentions that the Splicers have split up into two factions: one representing the "good" ending in BioShock, and the other representing the "bad" ending. The nine Minute Walkthrough has also revealed that you will no longer face one or two at a time because, with the player as a big daddy, that would be a splicer suicide. Instead they will attack in groups. Also should you kill most of them, the final splicer may attempt to flee. Also according to somethinginthesea.com the writer R. Killian Quain was strongly implied to be a former splicer. This indicates some of them have escaped Rapture to the surface. Some variations of splicers are still present such as Leadhead Splicers and Nitro Splicers as well as some new kinds of Splicers.