Arrow keys to move. Z to shoot. Space to slow down (focus). Deplete the boss's health before time runs out to capture the spellcard. If you run out of time or get hit, you fail.
For those of you unfamiliar with danmaku: "Danmaku" (弾幕) is a Japanese word for 'barrage', literally meaning "bullet curtain" or "curtain of fire" (quite aptly named, if you ask me). Usually, the hitbox of your character in these games is very small, much smaller than its sprite. One popular danmaku series is known as the "Touhou Project" (東方Project) made by Team Shanghai Alice, whose sole member is Japanese game developer Jun'ya Ota (太田順也), more commonly known as ZUN. It's where I got interested in the genre. If you can get past the fact that all of the main characters are anime girls and the fact that the series is quite hard (there's a difficulty called "Lunatic" for Pete's sake, and this would probably be an Easy (EDIT (1/8/15): I made this quite a bit harder, so now I'd say Normal or Hard) difficulty pattern) it's a really good series. http://en.touhouwiki.net/wiki/Touhou_Wiki I don't know why I'm putting all of this here, considering it's probably going to get max 10 views :P (UPDATE: Oh hey, it has 11 views :) (UPDATE 2 (Christmas 2013): Whoa, 158 views :O) DISCLAIMER: I do not own or claim to own the sprite that I used for the player. It is the property of Team Shanghai Alice, creator of the Touhou Project.