The fun from these kinds of games is playing it on the hardest difficulty (in this case, Lunatic) on regular (not practice), and using no continue bullshit.
Basic controls. Z to fire, X to use a special ability, arrow keys to move. Shift does something, too, but I haven't bothered testing out the whole game yet. By the way, when you open the window, click on the image first, then use the arrow keys to select things, as it is layered rather than embedded. Good luck.
Edit: Shift changes your combat mode. It slows you down but focuses your shots; good for taking down bosses. Also, moving near the top of the screen allows all of your bullets to auto-lock onto any enemy on screen and blow the living hell out of them, and it makes all dropped upgrade card things warp directly to you so you don't have to dick around picking them up. Also, I have only played the first character; if some of this information doesn't apply, say as much.
I'd practically forgotten about this. Beat it on Lunatic; 450 million. Afformentioned friend took it upon himself to beat all the Japanese players, and scored 912 mil. It's all just bullet pattern recognition. Keep in mind that your hitbox is incredibly small.