The App Store is the epitome of the term "mixed bag". If you're willing to dig deep enough you can find just about anything in there and the store is still growing rapidly. The offering ranges from useful apps that have you ask yourself again and again how you could have ever lived without them before as well as possibly somewhat less useful apps like virtual whoopee cushions, pimple poppers and kebab skewers slowly rotating on the screen. With the gaming section being by far the biggest on the App Store, variety there is obviously just as big, if not bigger, both in terms of contents and quality. There are all kinds of seemingly haphazardly tucked together monstrosities born out of a boring lunch break, uninspired clones of clones of clones of old clones of games that once might have been regarded as being creative in a way, some more uninspired clones done by big companies trying to make a quick buck by tacking on some of their franchises, (sometimes bizarre) ports of older games (Alpine Racer? Really, Namco?) for the most part without any consideration as of whether a button-less device is even up for the task, genuinely great indie games, neat diversions for boring lunch breaks (take note, shoddy app developers. This might be a better way for you to spend your time.), huge big-name apps with amazing visuals that even play a lot better than they have any right to do with a virtual d-pad, etc.
Amidst the huge selection of games there is more than enough space for a few niches, which even allows genres mostly dead on other devices to somewhat bloom again. Take Beat 'em Ups for example. Sure, Final Fight was an anticipated release when it finally hit XBLA and there's also the inexplicably popular Scott Pilgrim vs. the World and Castle Crashers, but otherwise the genre unfortunately is mostly a relic of old days, with once prolific companies like Konami, Sega and Capcom shunning away from it or others like Technos simply not being around anymore. On the iPhone on the other hand we not only have some ports of old classics, but also quite a lot of newly developed titles (if only rather bland ones, for the most part) and a brand new Double Dragon. Or text adventures. The only prominent appearance they have made outside of the iPhone was as a gimmick in Call of Duty Black Ops, which was probably a waste considering your standard Call of Duty demographic. On the iPhone though we have at least an absurdly overpriced port of Mystery House as well as Frotz, which features myriads of new text adventures as well as old classics. Arguably the most prolific genre of the old days on the App Store, though, is the good old Shoot 'em Up. Heck, even Electronic Arts of all companies has a shooter in its catalogue.
Of course there are your standard Space Invaders clones (another product of those boring lunch breaks?) and some shoddy game collections priced at a mere buck feature even shoddier shooters and the dual-stick hype made popular by Geometry Wars delights us with a lot of me-toos, but you can also find some competent ports, good games obviously inspired by true classics and best of all: Except for the Cave games they're mostly dirt cheap. An interesting tidbit about iPhone shooters is that a considerable amount of them are made by Chinese for whatever reason.
This article is split up into eight parts: The first one covers all vertical scrolling shooters, while the second one focuses on the horizontally scrolling ones (go figure). The third section will take a look at dual-stick shooters, which is first followed by other arena-based shooters, then by restrictive shooters and then by a section about anything else in the genre usually with games mixing different styles or genres. The second to last part covers game collections that happen to among others also contain retro shooters. I originally intended to cover every single collection with shooters in them, until I came to realize that there are way too many of these and basically none of them are truly interesting, since they are shoddily designed and executed fillers, scraping the bottom of the barrel even more than some of the worst stand-alone shooter releases. The final part covers other apps with a shooter theme. Wait, bear with me! You'll come to understand.
While the first two groups of games should be easy to classify for the most part, others can prove to be more difficult, especially dual-stick shooters, which easily border on action games like Gauntlet, Commando and so on. Some people will possibly disagree on some of my decisions as to what qualifies as a Shoot 'em Up and what doesn't, but I'm always open for discussion on the forums. As of now, games such as Minigore, iDracula, Battle for Cydonia and Bug Heroes are not included, simply for not feeling like a shooter, even though, yeah, you actually shoot in them. And quite a lot at that. Plus, the majority of a game has to be in a shoot 'em up style, so no Choplifter-style games as they tend to equally focus on keeping your craft under control, rescuing people and shooting and also no Metal Slug Touch, despite its sidescrolling flying stages, sorry. What's more, I don't count games such as Gunner Galaxies or Chromanoids where you control a static gun turret leaving you unable to move like in Missile Command. As a general rule of thumb, the later a game is listed in its section, the less worthwhile it is. So for example the first horizontal shooter is arguably the best one and the last vertical shooter is least likely to set your gaming world on fire. I try to pack sequels together for the most part, though, so sometimes there might be a game listed a bit higher than it actually deserves just for the reading convenience. Also, as it is nigh impossible to keep track of the whole App Store, I will probably have missed a few shooters, so I'd appreciate any heads up on other games for me to add to the article.
Ok, as of now, I do have left out a couple of games, mostly because they are too expensive for how (un-)interesting they look, but I will eventually cover these as well: Ace Omicron / Fast Striker / PewPew 2 / Alien Invaders 2 / BattleSquadr1 / MetalAngel / Ultranium 4 / Chromium ES / Air Combat / AeroNauts / Cave Shooter 2