Here's what I thought of for my "version"...

5 Difficulty Settings

up to 15 different Boosters (like Power Ups in other games)

3 Sizes of Space Rocks (Asteroids)

Space Junk (4 types)

3 types of UFOs

various Mineral Ores (collected from destroyed Space Rocks)
I have some things worked out, but others I can't quite grasp...
I can write the logic out in English, but getting the computer to do it in that same fashion seems to be a stretch... >_<
I know I'll eventually get it, but I need to figure out how and where to create 'waves' and such.
With the backbone and 'radar' that I have available to me, I'm trying to figure out how to build the "world", implement a "skybox" and insert "waves" of enemies and rocks.
I envision it much like "Blasteroids" with planets (or a nifty outer space picture) behind the 'playfield'. The rocks and stuff just above it, and your score and ship properties above that on a HUD or something with a radar.
Does this sound too extensive? Does this sound like I've taken on more than I can handle?
Any suggestions?
Thanks in advance for any advice...
~Ani