We've been so busy at work. Crunch time on our latest project.
Anyway, to respond to a much earlier post, the Tyrian 2000 thing was kind of... weird. Although if I recall it was actually a fair number of missions, it ended up strange for various reasons which are amusing but I probably shouldn't post about. (Hint: It involved fermented beverages, though not on my part.) It was a little frustrating to make.
If you want an example of a decent-looking 3D shooter, Nanostray 2 comes to mind. I find it a bit boring but probably because there isn't much depth to the gameplay. However, it's quite pretty even on a DS. Actually if you look to Japan they still manage to publish various shooter games, the most successful of which seem to adhere to one pronounced gimmick or another.
So the question between 2D and 3D is a difficult one. I would say the correct answer is that 3D is worse until it's 'good enough'. Which tends to mean you have to do a good job with it and have enough polys/detail to look as good as 2D (or close to and be saved by the motion of the game making up for it).
Moving up and down in the Z plane would introduce unusual gameplay problems. When I play that in my head I find the complexity of deciding which plane an enemy is on (large spaceships might look like they're higher up to the player at first), being covered up by higher Z objects, etc. There have been a number of Japanese games to introduce a ground world to bomb along with flying ships. I suppose Tyrian had a little of that, but they tend to differentiate buildings as generall far-down objects you have to use bombs on. These seem like they would be tricky to get the gameplay balance right, because all too often you end up having to split your attention too many ways.
And yes, shooters tend to sell a lot less for several reasons.
1. The most obvious of which is that the market is generally smaller. People don't want to pay 30 bucks for an action game that is fun for 30 minutes, as most shooters tend to be anymore. Which is the second reason..
2. That many (especially the most mainstream games) tend to introduce no/few new gameplay concepts. Flying around and shooting at ships is not really all that much fun anymore if there's no variety to it. It's hard to go back and play Galaxian all day, now. But space/action tends to not interest a large number of people, at least the people who have money.
3. And the final thing is that, reflected by the earlier reasons and others, sales will be very low next to games with much higher perceived gameplay. People will not use word of mouth to recommend it to their friends and review sites will destroy the game in reviews. IE, the length of time it will be a viable product will be extremely short. I have several games like that, which I'd happily loan out to friends, but when they ask me what they're like I say something like 'Well, it was okay, but the mission sequence was derivative and they resorted to a meaningless powerup system which just ended up being a waste of time when it could have been the coolest thing since sliced bread.' (Recent spaceflight game.)
You can argue that yes, if a really good game came out that was shockingly good people would buy it and it would buck the trend, but it would be a very hard sell to a company that a shooter would be worth spending a million bucks on. At least in this day and age when marketing looks at games like Zelda and Pokemon and see huge dollar signs. It might even be possible to break the 'mold' as it were and create something truly phenomenal that people would want to play.
Sometimes I think about doing that, though I have to admit that life gets more complex when you get older. People seem to expect you to do mundane things like pay bills and fix your car and junk. Imagine that!
Even the 3D space flight sims, which I love to play, are riddled with so many bad 'clones' and has barely evolved (in essence) past the Wing Commander/Prophecy days. They look really pretty, but you can be assured that most will have the exact same gameplay (as in a set of about 5 unique mission types, 6-12 enemy ship types, a few capital ships, and a bunch of meaningless worlds with a screen interface for trading things). You're also lucky if the plot is anything but mysteriously written by pixies and is at all engrossing. (I yearn for another Freespace, I guess.)
So, perhaps in the end the shooter market was just so saturated with clones and endlessly repetitive but nice looking arcade games that people really don't want to give it a chance now. Not when a lot of them are addicted to WoW and the like and have discovered the social aspect of gaming.
But I digress! And opinions are just that, and mine change every year or so.
I would point out I made Tyrian mostly because I had nothing fun to play when I was a kid. There weren't all that many good games out and we couldn't afford game systems with too many games. Probably too much free time, too.
That may be why it turned out to be so much fun. I admit I was always a little surprised everyone else liked it so much, but at least I finally got used to that idea.