Fixed shooters are games where the protagonist is fixed at one position on the screen, being able to only change the angle of shooting or strafe (usually, this is a story about a gun turret). The most notable example is, of course, Space Invaders. Another one is a classic game, Paratrooper, originally designed by Greg Kuperberg in 1982. Now, there are dozens of clones of this product on iTunes; its concept is very addictive.

A screenshot from DOT Space Hero by 1Coin

Scrolling shooters are games where all the actions are shown from a side-view perspective. Originally, such games were sprite-based, being a direct analogy to platform arcade; the only difference was the more dynamic action-oriented gameplay. Such games were extremely popular on 8 bit and 16 bit gaming consoles because many modern developers tried to contribute to them. A wonderful example is DOT Space Hero from 1Coin (http://www.dotspacehero.com/). The game has amazing and cute graphics as well as colorful gameplay. The general advantage of side-scrolling concept for iOS devices is an easy to control system.

Rail shooters are games where the player cannot freely move around. The game moves the avatar from one location to another, and allows him to fight with the enemies while running or in special zones. The system works like a sightseeing train in an amusement park. The concept is ideal for arcade-shooting galleries; once all the enemies are down, the game moves you to a new intact location. Of course, the lack of freedom is a bad idea, but sometimes such mechanics may help you manage some issues such as tricky shooter controls on touch-screen devices. Since a player does not need to guide the character themselves, they can concentrate only on shooting. A popular instance is Rage HD developed by id Software (http://www.idsoftware.com/iphone-games/rage-mobile/).

First-person shooter (FPS) are games that demonstrate the 3D gaming world through a first-person perspective. In other words, they try to be as close as possible to the natural human perception of reality. Now, this is one of the most popular types of shooters, especially on computers and gaming consoles. The iOS platform is not an exception. There are several very interesting ports of classic FPS games as well as projects that are developed specially for it, for example, Deus Ex: The Fall from Square Enix (http://www.deusex.com/thefall).

The general weak point of FPS on touch-screen devices is the controls that hold back their popularity on the platform a little bit.

Deus Ex: The Fall used dual cameras. Being a first-person shooter, the game switches to third-person view on special occasions to express some specific actions in a better way.

Third-person shooters (TPS) are 3D games where a player may not only see the gaming environment around, but also his own avatar. The virtual camera is placed somewhere behind him since the gameplay is very similar to FPS games, but the player can see the animation of the main characters. This is good for games with complex actions such as jumping, crouching, and balancing. There is also a belief that the audience is more attached to characters that are shown in full form when a 3D figure of the protagonist is displayed at the screen, so all its graphic details and animated movements can be easily noticed. There are two basic ways of using a third-person perspective in games. The first is a traditional view showing the back of the protagonist; the camera is slightly above him. And the second one is the so-called over-the-shoulder view when the camera is almost hidden under the character's back, being placed in the line of his sight. The player sees the world over his shoulder. Such a combination is a little bit clumsy, but it helps to aim in a better way. This type of camera is very suitable for the horror genre because it is hard to turn around fast since there is always a fear of what is behind. This feature is successfully used in the Dead Space franchise published by Electronic Arts.

Mixed shooters are a combination of other genres, for example, action-RPG, action-adventure, and action-survival. The eclecticism is now in fashion. Most modern action games are a mix of different mechanics. It helps to enrich gameplay with new features. Among the popular titles for iOS in this domain are the successful franchises Infinity Blade from Chair Entertainment (http://infinityblade.com/) and Epic Games. They combine the advanced 3D graphics, accurate character, environment design, interesting combat mechanics (based on sword fighting and not guns), and RPG elements.