Shooting code.

The really neat thing about these games (for the coders in the audience) is that the bullet patterns are not predetermined, but are instead generated using an engine that reads an XML document.

Ikaruga: The well-tempered video game.

Unlike the story-driven games that are so popular nowadays but are only good for a single playthrough, the durability of play in a neoclassical shooter like Ikaruga lies in repetition and the quest for perfection.