What I was really trying to do while playing Tyrian was get ideas for enemies, so I decided to categorize the enemies. It was actually sort of depressing once I was done, because it definitely takes the wonder out of playing...
Click on the titles for screenshots, Tyrian wouldn't let me with Prnt Scrn and I just don't feel like dealing with FRAPS.
The basic cannon fodder, take 1-2 shots to kill.
These are pretty much the meat of the game, they come onto the screen in random or semi-random spots. They aren't much of a threat in small numbers, if you have the shields, you can just plow through them without much of a problem. There are only a few flavors, which depend on 3 things : Health, where they appear from, how they maneuver, and whether they fire bullets. The first three determine both how difficult they are to destroy, with the maneuvering and starting position really deciding how fun they are. It's pretty fun when they come in a snakelike pattern and you can just line up and blow them away one by one... (we'll have to copy that).
Big Guys- Take more than ~2 hits to kill, persistent.
These are essentially higher-grade cannon fodder. Like the Throwaways, some shoot and some don't. What's interesting about them in Tyrian is that they are often made up of several smaller units that can be destroyed separately. This is nice because it makes it very apparent the player is doing damage, and it allows them to "transform" by moving components around, which is a helluva lot easier than animating it by hand. They also take up considerably more space, which is significant given the rather limited play area.
Ground-Based- Turrets and Tanks
Ground-based- move on tracks or on paths (rails), can shift position and continue firing, but have much less mobility than flying units. They also more often have tracking projectiles to compensate. We can't really do much with these because to save about 897,239,485 hours of drawing time and have the whole shebang in space. Unlike most the throways, a lot of them persist on the screen, staying with the player (as the world scrolls) until destroyed.
Obstacles- Moving or not moving, kill or damage player on contact.
These are the obvious things you can't touch on the screen, but that are static (in relation to the scrolling). In one of the first levels there are in fact giant claws that come out of cliffs that you have to avoid. It reminded more of Super Mario Bros. rather than a shooter, but whatev. A more relevant obstacle were the shields, which are plausible for our universe (more on that in a later entry). Basically, they bridged a gap until they absorbed enough damage to fail.
Bosses- The grand finale of most levels, they are essentially take up a lot of space, forcing the player to move carefully as various pieces fly at the player and dozens of energy balls float around.
After playing Tyrian, it's pretty apparent the game is as much about obstacle avoidance as actually shooting things. It's pretty obvious that most of the "bullets" in the game or basically just little obstacles, especially when they come in streams. The boss battles can be thought of in terms of "safe space" and "dead space" in particular, with the safe area constantly shifting, adding on a significant layer in addition to just shooting. That sums up the entire game pretty well.
We're going for a little different balance of fundamental gameplay, but once again, more on that later...
As a parting shot, here's the work-in-progress version of the new carrier:
Player and AWACS to scale.