Well i found this neat game call Fraxy, basically what you do is fight giant bosses, that can have parts detach as little ships, it also has a mode where you play a mission where preset waves come at you.
One Awesome feature is you can create you own bosses using a simple drag and drop editor, and you can make missions.
You can get it here
http://mokeron.hp.infoseek.co.jp/zg/fraxy_main.html the site is in japenese, but theres a version that says english only.
Her is a picture of a character i made
I'm a noob help will be accepted