Scrolling Shooters

Okay the point of this topic is basically:
When you play a scrolling shooter what features tend to make you enjoy it or want to play it more?
By scrolling shooter I mean the games like the classic Aero fighters series or Raiden.

List any number of features you like that draw you to that kind of game.

The reason for my asking is that I am going to make one and would like to please as many people as possible, If I made it solely on my prefrences I feel it may not please others.

So please if you have any prefrences list them for me.
Please don't say graphics... I can only do so much...

Also the poll above is to ask what levels and kinds of difficulties people prefer. Basicly as example [Easy, Swarms of enemies] means that there would be enemies that move in groups in patterns and [Average, Swarms of enemies] would mean that there would be a lot of enemy swarms moving in patterns kind of thing. I'll basically balance out the replies I get when designing the levels.

I don't play a lot of shooters, but in just about any game, I prefer tougher enemies than hordes of nobodies. But, please don't make 'tougher' just mean better armor. Although that works well sometimes, it's also nice to see different attack patterns that challenge your thinking or require better maneuvering.

Oh no worries on that end. If nothing else I am inventive. I already think I have an interesting first boss planed out.

One of my preferences is for my enemies to have attack variety so unless others think its lame then that's how It will be.

Nice. All is good then.

No one else?

Well, at least the few answers average out at something. This community really needs more dedicated people.

I'm noticing that....
You'd think that at least the mods would drop in a comment...

Well, Soul had something going on and can't be that active, but the admin for sure.

admin, mods.... same thing to me.

Yeah, I know. I was using 'admins' to group Luke and John, not point out the distinction. What's the theme of this shooter going to be? Futuristic/space ships? World War aircraft? Cavemen on Pterodactyls? Wizards on dragons? Bikers on hotrods with bazookas? So many possibilities.

Actually... I think they can be called psychics.... maybe...
Basically a group of psychics... maybe... are fighting off a demonic invasion of the earth... that kinda sums it up...

Each playable character hails from a different country 6 in total as of the moment. Represented are United States, Japan, France, Britain, Egypt, and Brazil. Each with entirely different attacks and specials.

Whoa. That's neat. Not at all what I was expecting.

Yeah for the countries I basically threw a dart at a spinning globe... then jumped out of the room and realized what a dumb ******* idea that was... so I just picked them like normal...

Haha. Weird. I bet you got half of them in the ocean too.

No the first one I threw is lodged in my wall... I stopped after that... Throwing darts at a spinning globe makes the darts bounce apparently...

Ah, well, I had made the assumption that the globe was penetrable. I guess I'd stop too after marring the wall.

Why else would I have jumped out of the room immediately after throwing the dart I wonder?

Oh come-on peeps, I'm about to get to the level design phase of the programming, I need some opinions. This is for you people, not me.