Amazing how many people are confusing platformers like G'NG and SMB, as well as run-n-guns like Contra and Metal Slug with shoot em ups, aka shmups, in this thread. Anyone remember the SHMUPFAQ? Malc described them as follows:
"Tricky one this, and full of pitfalls if I don't answer right, with loads of anal-retentives ready to jump down my neck at a slip...
The word SHMUP originated as a compressed form of the term SHOOTEMUP, a label applied to a certain type of game which involved you playing a character shooting things. As far as I can work out, SHMUP seems to be a UK term, and I'd love to know who made it up!
But exactly what type of game is a shootemup then? I'd like to just say that when you know that you don't need to ask what a SHMUP is, then you know. But that's a pretentious load of bollocks, and I wouldn't get away with it.
So how can I do it then? I'm must admit to having a wee break here, as I really don't know. Lets set some simple rules for a wannabe shmup game to be even allowed to know where the party's at:
It must involve you controlling an object which you use to shoot other enemy objects with. (ie, you must shoot things.)
But that would mean any old game like Duckshoot, Doom, Quake, Time Crisis and even Deerhunter could be called a shootemup, right?
Technically yes, so we obviously need to refine it a little more. Remember the terms SHMUP and SHOOTEMUP were coined when there wasn't any 3D polygons and CD games, and the most a machine could manage was some sprites flying about the screen and some basic scrolling.
To a veteran hard-boiled gamesplayer, this was the Golden Age. The subtitle on SHMUPS says something about CLASSIC shootemups - and we all know how hard 'classic' is to define as well!! We're talking the eighties and early nineties here, and what games typified a shooting game in the arcades?
For me, they were: Xevious, one of the first vertical scrolling games ever, Nemesis, which pioneered in many ways with its level/boss structure and of course R-Type, all three of these created a template which is still being used to fashion shootemups today.
So I'm going to define a shmup as this:
A videogame in which you control a flying spaceship / character in a scrolling 2-dimensional environment in which you shoot waves of enemy ships /aliens / bosses and avoid their firepower.
This is my interpretation, and it suits me fine. It's not a tight definition, and it might not be other people's idea of what a shmup is, but that's fine by me! You'll probably notice some games in here which don't exactly, or even nearly fit that definition, but they're here because they add variety and spice and they're damned good 'nearly-shmups'. Contra is one: it's a mix of action platform game and shmup. See if you can spot any others. But don't tell me about them because I probably know already."
They don't get enough respect as it is, people, so let's not just start throwing any old game into the mix.
Back to the original question: just about any game in the Gradius/Salamander/Parodius, ThunderForce, Darius or R-Type series are great. Sure, there are a few exceptions here and there, but for the most part they're all great. I also highly recommend Axelay, Einhander and Pulstar.